I absolutely love Halloween and all the spooky themed food that comes with it. These Halloween Slime Cupcakes fit the bill perfectly as they look rather scary with their black "burnt" sponge, bright green "toxic" buttercream and creepy candy eyes, but don't be fooled - they taste absolutely yummy! Once you bite into their menacing exterior you'll find gooey "radioactive" slime inside. I used green coloured custard to create this effect, but you could use strawberry jam for a "blood and guts" theme inside too. Kids and adults alike will love making these fun slime cupcakes to disgust and delight their family and friends over the Halloween season!
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Ingredient Tips & Equipment Information
- Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
- For the best results, use good quality professional food colouring. My favourite brands are Pro Gel and Sugarflair.
- I use a baking spread for the cupcakes and unsalted butter for the buttercrream.
- I got the candy eyes in my local supermarket and they are pretty widely available around Halloween, but you can purchase them online too. Do check the ingredients if you are vegetarian or if you have any allergies as some can contain insect derived food colourings, egg white or milk powder. Or you can make your own by melting some dark chocolate and piping a small circle onto a white chocolate button.
- Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
- For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.
For the full recipe with measurements, head to the recipe card at the end of this post.
How to make Halloween Slime Cupcakes
To make the cupcakes, mix together butter and caster sugar. Then add eggs and vanilla extract, and whisk in. Next, add self raising flour and black food colouring and mix in. Divide the batter between the black cupcake cases. Bake for 25-30 minutes, use a thin skewer or a cocktail stick to check they are done as you won't be able to tell by the colour!
When the cupcakes are fully cooled, use a cupcake corer or a knife, to make holes in the middle of each cake. Add a little bit of green food colouring to the custard, then spoon it into each cupcake. To make the buttercream, mix together the butter and icing sugar. Add the vanilla extract, milk and the green and yellow food colourings until you have a nice bright green colour. Pipe it onto the cupcakes then decorate with the candy eyes and sprinkles.
For the full recipe with measurements, head to the recipe card at the end of this post.
What is the best food colouring to use?
I recommend using a professional grade food colour for the best and spookiest results! I used Sugarflair Black Extra for the cupcakes. For the buttercream, I recommend either Pro Gel Lime Green, or a mixture of Sugarflair Party Green and Sugarflair Melon Yellow. There are lots of other good food colouring brands, such as Colour Mill and Americolor. You can buy them all easily online.
What else can you fill the cupcakes with?
I chose to fill the cupcakes with tinned custard that I coloured green with food colouring. You could also use lime or lemon curd or lime marmalade, and again add some food colouring to them for the slime effect. You can of course leave the cupcakes unfilled if you prefer.
How long do the cupcakes last for and can they be frozen?
The cupcakes will last for 2-3 days in an airtight container in a cool place. You can freeze both the cupcakes and the buttercream. To freeze them separately, wrap the cupcakes well in cling film or put them in an airtight container. The buttercream can be frozen in a sealed tub. To freeze them decorated, freeze the cupcakes on a plate until frozen solid, then carefully wrap in cling film. Remove the cling film when you take the cupcakes out of the freezer to defrost, as if they defrost with it still on it could damage the buttercream.
Can you make the cupcakes with plain/all purpose flour?
Self raising flour, which is very commonly used in the UK where I am based, already contains a raising agent and a little salt too. Therefore if you want to swap it for plain or all purpose flour, you will need to add some additional baking powder and also a little salt if you like. Some people like to add salt to cake recipes and some don't, so I'll leave that up to you as it won't affect the bake. The general advice is to add 2 teaspoons baking powder (a measuring teaspoon, not the kind you stir your coffee with) per every 200g plain or all purpose flour. So for this recipe you'd need to add 1 + ½ teaspoons baking powder. Please note, I have not tested this recipe using plain or all purpose flour.
Is butter or a baking spread better for cupcakes?
I prefer to use a baking spread (my preferred brand is Stork) for cupcake and cake sponges. I find that they are easier to use and they make the sponge rise more. You can also use most baking spread straight from the fridge, which is handy during a last minute baking emergency!
Should you use salted or unsalted butter for cupcakes?
I always use unsalted butter and baking spread for baking. This is because if you want to add salt to your recipe, you then have complete control of the salt level. Lots of people add salt to enhance the flavour of baked goods, so when you do this you want to know exactly how much you're adding. I personally prefer not to add salt to cakes and cupcakes. However, using a salted butter or baking spread will not affect the bake negatively and won't make it taste salty.
Can the cupcakes be made gluten or dairy free?
Yes! For gluten free you can replace the self raising flour with a gluten free self raising flour blend. If you only have a gluten free plain flour blend, you will need to add baking powder. The general advice is to add 2 tsp baking powder per 200g flour, so for this recipe you'd need to add 1 + ½ teaspoons baking powder. You may also like to add ¼ tsp xanthan gum for better texture. For a dairy free version, use a dairy free baking spread for the cupcakes and the buttercream. If you are using candy eyes, check the labels as some can contain milk powder. Please check the labels of everything you use if serving to someone with an allergy or intolerance.
More tips for making the Halloween Slime Cupcakes:
- I used a Jem 1E nozzle to pipe the buttercream onto the cupcakes, but you can use any nozzle you prefer or spread it on with a spoon.
- You can decorate the cupcakes with any Halloween themed sprinkles you prefer.
Troubleshooting
If you have any questions about this recipe, or if something went wrong and you need help, please use the comment form below and I will get back to you. You can also get in touch with me on my Twitter, Instagram or Facebook. I'd love to hear from you!
Recommended equipment & ingredients
- Cupcake tin
- Mixing bowls
- Cooling rack
- Kitchen scales
- Electric hand mixer
- Piping bags
- Cupcake corer
- Black cupcake cases
- Lime green food colouring
- Black food colouring
- Jem 1E Piping nozzle
- Candy eyes
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More Halloween cupcake recipes...
Halloween Slime Cupcakes
Ingredients
For the cupcake sponge
- 175 g Baking spread (or butter) softened, unsalted
- 175 g Caster sugar
- 3 Eggs large
- 2 tsp Vanilla extract
- 175 g Self raising flour
- 25 g Black food colouring
For the buttercream
- 200 g Butter softened, unsalted
- 400 g Icing sugar
- 1 tsp Vanilla extract
- 1-2 tbsp Milk
- Green food colouring
- Yellow food colouring
For the filling and decoration
- 150 g Tinned custard
- Green food colouring
- Candy eyes
- Green sprinkles
Instructions
- Pre-heat your oven to 140C Fan/325F/Gas Mark 3, and line a cupcake tin with cupcake cases (ideally black ones)
- For the cupcake sponge, mix together the baking spread and caster sugar, ideally using an electric mixer, for 5 minutes until smooth and fluffy
- Add the eggs and vanilla extract and whisk them in well
- Then gently whisk in the self raising flour
- Add the black food colouring and mix in well
- Divide the mixture between the cupcakes cases, and bake them for 25-30 minutes or until a skewer inserted in the centre of the cupcakes comes out clean. Put them on a rack to cool completely
- Once the cupcakes are fully cool, use a cupcake corer or a knife to make holes in the middle of each cake
- Add a little bit of green food colouring to the custard and mix it in, then spoon it into each cupcake
- Make the buttercream by mixing together the butter and icing sugar until smooth, then add the vanilla extract, milk and the green and yellow food colourings until you have a bright green colour. You can add more milk if the buttercream is too stiff
- Using a piping bag, pipe the buttercream onto the cupcakes. Or spread it on with a spoon. Decorate with the candy eyes and sprinkles
- Store in an airtight container in a cool place, eat leftovers within 3 days
Video
Notes
- Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
- For the best results, use good quality professional food colouring. My favourite brands are Pro Gel and Sugarflair.
- I use a baking spread for the cupcakes and unsalted butter for the buttercream.
- I got the candy eyes in my local supermarket and they are pretty widely available around Halloween, but you can purchase them online too. Do check the ingredients if you are vegetarian or if you have any allergies as some can contain insect derived food colourings, egg white or milk powder. Or you can make your own by melting some dark chocolate and piping a small circle onto a white chocolate button.
- Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
- For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.
Cat
What a fantastic idea for Halloween! Especially like the slime filling which I think is really creative x
thebakingexplorer
Thanks so much Cat!
Rebecca Smith
What a brilliant idea love this...in fact, that's one day in half term sorted...kiddies are making slime cupcakes (with a wee tweak to make them free from) #CookBlogShare
thebakingexplorer
Thanks Rebecca! I do hope you and your family enjoy them!
Charlotte Oates
These look delicious Kat. I love the idea of using marmalade to make green slime, the extra food colouring really gives it an amazing colour.
thebakingexplorer
Thanks Charlotte! I did have to use a lot of black food colouring, but the effect is worth it for a one off treat!
Nico @ yumsome
These are brilliant! I particularly love that they're filled with green slime as well as having a toxic green top. Fantastic!
Of course, now I have a hankering for Rose's Lime marmalade, which I've not even seen for years, much less had any! 😉
#CookBlogShare
thebakingexplorer
I used Rose's Lime marmalade, I found it in Tesco!
Lucy
Wow these are so striking Kat! My kids will adore these, we’ll have to give them a go over half term. Love the green slime effect, so cool.
thebakingexplorer
Thanks Lucy, let me know how they get on I'd love to see!
Corina Blum
These are fantastic! I'm not keen on orange marmalade but I love lime marmalade and would definitely like to try these. They sound so tasty as well as looking great.
thebakingexplorer
Me too Corina, I'm not a fan of standard orange marmalade but I really enjoyed the lime one!
jenny paulin
I love these - so cute and yet very easy to achieve. Lime marmalade for the slime is brilliant!very clever x
#Bakeoftheweek
thebakingexplorer
Thank Jenny!
Helen
These look fab! You've got a great colour on the sponge & the icing!
thebakingexplorer
Thanks Helen! I'm really liking the ProGel food colours at the moment!
Kirsty Hijacked By Twins
Oh wow Kat these look fantastic! The kids would definitely love these! I love the vibrant colour of the icing. Thank you for sharing with #CookBlogShare x
thebakingexplorer
Thanks Kirsty! People did seem to be very attracted to the bright colours!
Jacqui Bellefontaine
How much fun are these I love them!
thebakingexplorer
Thanks so much Jacqui!
Claire
These are brilliant. What a great idea 🙂
thebakingexplorer
Thanks Claire!
Petra
This is a recipe that makes me smile! It must be the cutest Halloween treats I have seen! Happy Fiesta Friday 🙂
thebakingexplorer
Wow Petra, that is high praise - thank you!
Nate
What are a great idea Kat. My daughter is obsessed with slime so these would be a huge hit with her. Thanks for sharing the recipe.
thebakingexplorer
Thanks Nate! I hope she likes them!
Angela / Only Crumbs Remain
These are absolutely brilliant Kat! Loving the toxic buttercream, and as for the radiocative slime! Genius 🙂 Thankyou for joining in with #BakingCrumbs too 🙂
Angela xx
thebakingexplorer
Thanks so much Angela and thank you for hosting!
Kate - gluten free alchemist
So cute! What a great icing colour too..... Perfect for Halloween x
thebakingexplorer
Thanks Kate, I used ProGel colour in Lime Green.
Michelle
I have got some food colouring from Aldi, The Pantry. Will this be okay to use please
thebakingexplorer
Hi Michelle, it probably won't be strong enough unfortunately, but you can try it out.
johanna @ green gourmet giraffe
these look so cute - I made bikkies last halloween using black tahini and it really made them so dark - I would love to try these cupcakes with black tahini but I don't think I could pipe the toxic icing as prettily as you