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This Hidden Heart Chocolate Loaf Cake is made using the hidden design technique, it looks so impressive and clever but is easier to make than you think! There are lots of different ideas out there of what image to hide inside, but this is a good one to start off with if you want to give hidden designs a go for the first time. Plus it's perfect for Valentine's Day! As well as it's pretty apperance, it's a delicious chocolate cake with a rich buttercream that's infused with dark chocolate - so yummy! The most exciting part is the moment of truth when you cut into it and see the design inside, it's such a fun surprise especially if you don't tell your friends and family about it! It will certainly provide a romantic surprise too if you bake this for your loved one.

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 flavour, make sure to use a good quality vanilla extract and not an essence.
I used a baking spread for the cakes and unsalted butter for the buttercream.
You will need to use a professional grade food colouring to get the same shade of pink that you can see in my photos. Brands I recommend are Pro Gel and Sugarflair. Colour Mill and Americolor are also good quality brands.
You will need a 2lb loaf tin for this recipe (you can test the size of your loaf tin by seeing how much water the tin can hold, 2lb will hold about 2 pints/1100ml of water). If you have a 1lb loaf tin, simply halve the ingredient amounts.
For easy lining of the tin, use a loaf cake tin liner*.
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 Hidden Heart Chocolate Loaf Cake

To make the pink sponge mix together baking spread and sugar. Then add eggs and vanilla extract, and mix them in. Finally mix in self raising flour and enough pink food colouring to get a strong shade.

Pour it into a loaf tin and bake for 50 minutes, then leave it to cool completely.

When it is fully cool, cut off the ends of the sponge, then score marks along it the same thickness as your heart shaped cutter. Cut the sponge into pieces following the scored marks, and then use your heart shaped cutter to cut out hearts from each piece. You can use the leftover cake to make Three Ingredient Leftover Cake Truffles, so don't throw it away.

To make the chocolate sponge, mix together baking spread and sugar. Then add eggs and milk, and mix in. Finally fold in self raising flour, baking powder and cocoa powder. Put a little bit of the cake mixture into the bottom of the tin, and set the heart shaped pink cake into it as neatly as you can in a row.

Spoon or pipe the remaining mixture around and on top of the pink sponge and bake it for 50 minutes. Leave to cool fully. To make the buttercream, mix together butter, icing sugar, vanilla extract and milk. Then add in melted dark chocolate and mix until smooth. Pipe the buttercream over the fully cooled sponge and sprinkle on some heart sprinkles.

For the full recipe with measurements, head to the recipe card at the end of this post.

What can you do with the leftover cake cuttings?

Make my easy no bake Three Ingredient Leftover Cake Truffles with the leftover cake! You could also make cake pops or cakesicles.

How should this cake be stored and can it be frozen?

The cake will keep in an airtight container for 3 days in a cool place. You can freeze the sponge either alone, or decorated. Once the sponge is fully cool, wrap well with cling film or put it in an airtight container. You can freeze the frosting on it’s own in a tub, or you can decorate the cake and freeze it fully assembled. To do this and avoid damage to the decoration, freeze it either in an airtight container. Or let it freeze solid on a cake board or plate, then wrap in cling film. Remove the cling film when you take it out to defrost it, if you don’t it could damage the decoration as it defrosts and softens. You can also freeze slices of the cake, again well wrapped in cling film or in airtight containers.

What is the best food colouring to use for the pink cake?

To get a bright pink shade that remains strong after the cake is baked you need to use a professional grade gel food colouring. You can buy these easily from many online shops, including Amazon. I use the brand Pro Gel, other brands include Colour Mill, Americolour and Sugarflair.

What size tin do you need for this recipe?

You will need a 2lb loaf tin for this recipe (you can test the size of your loaf tin by seeing how much water the tin can hold, 2lb will hold about 2 pints/1100mls of water). I do not recommend using a 1lb loaf tin as the cake will not be deep enough to create the hidden heart effect.

Can you make this loaf cake 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. Please note, I have not tested this recipe using plain or all purpose flour.

Can this loaf cake 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. You may also like to add ¼ tsp xanthan gum to each cake for better texture. For a dairy free version, use a dairy free baking spread for the cake and the buttercream, and a dairy free milk for the buttercream. You will also need to use a dairy free dark chocolate for the buttercream.

More tips for making the Hidden Heart Chocolate Loaf Cake:

I used a Wilton 1M nozzle to pipe on the buttercream.
The heart shaped cutter I used measures 4.5cm wide and 4.5cm high.
I find it easier to put the chocolate cake batter into a piping bag and pipe it around the pink sponge, but you can spoon it in too.

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*

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