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Lemon Rainbow Cake
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Lemon Rainbow Cake

Multi coloured rainbow cake with lemon curd filling
Course Dessert
Cuisine American
Keyword Cake
Prep Time 40 minutes
Cook Time 20 minutes
Total Time 1 hour
Servings 20
Calories 939kcal
Author thebakingexplorer

Ingredients

For the sponges

  • 550 g Butter or baking spread softened, unsalted
  • 550 g Caster sugar
  • 4 Lemons zest only
  • 10 Eggs large
  • 2 tbsp Milk
  • 550 g Self raising flour
  • Red, yellow, orange, green, blue and purple food colouring I used Rainbow Dust Pro Gel

For the buttercream and filling

  • 600 g Butter softened, unsalted
  • 1.2 kg Icing sugar
  • 2 tsp Vanilla extract
  • 4-5 tbsp Milk
  • 275 g Lemon curd good quality shop bought or homemade

For decoration

  • Rainbow sprinkles

Instructions

  • I own three 8" cake tins so I did three layers of the cake at a time. Only make as much mixture as you have cake tins for as you must not leave cake batter sat for a long period of time as it will affect the final result. To figure out how much you need for each layer, divide the cake ingredients by six. You can also buy disposable foil cake tins if you don't want to invest in more cake tins, but I recommend having at least three of the same size as there are lots of cake recipes on my blog that require three 8" tins!
  • Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line your 8" cake tins
  • Make the first three sponges by mixing half of the butter and caster sugar in a large bowl ideally using an electric mixer
  • Add half of the eggs, milk and lemon zest, and whisk until fully incorporated
  • Add half of the self raising flour and whisk in until you can't see any flour anymore
  • Divide the mixture equally between three bowls, add red food colouring to one bowl, orange to another and yellow to the last one. Whisk until the desired colour is achieved
  • Divide the mixture between the tins and bake for 20 minutes or until a skewer inserted in the middle comes out clean. Remove from the tins and leave them to fully cool on cooling racks
  • Wash the tins, re-line and grease them, then repeat steps 3 - 7 but add the green, blue and purple food colouring instead
  • To make the vanilla buttercream mix the butter and icing sugar together. Once it starts to come together add the vanilla extract and milk, and mix until smooth. For best results use an electric mixer. You can add more milk if it is too stiff
  • Start stacking the sponges on a plate or turn table. Spread a thin layer of buttercream onto each sponge, followed by a generous drizzle of lemon curd, before adding the next one
  • Once the sponges are all stacked and filled with buttercream and lemon curd, cover the whole cake in a thin crumb coat of buttercream. Put it in the fridge for an hour to firm up
  • Remove from the fridge and spread on a final and thicker layer of buttercream and smooth it out
  • Put the remaining buttercream into a piping bag fitted with a nozzle of your choice and pipe some small rosettes around the edge of the cake
  • Fill the middle of the top of the cake with rainbow sprinkles, and use a brush or your hands to add more sprinkles to the bottom edge of the cake
  • Leftovers will keep in an airtight container for 3 days

Notes

  • Make sure all your ingredients (particularly the eggs and butter) are at room temperature before you start baking.
  • I prefer to use a baking spread like Stork for the cake, and unsalted butter for the buttercream as I find they provide the best results.
  • For the best results, use good quality professional food colourings. My favourite brands are Pro Gel and Sugarflair. You can buy these easily online. Other well known brands are Colour Mill and Americolor.
  • If you would like to make your own lemon curd for the filling, check out my Homemade Lemon Curd recipe.
  • 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.

Nutrition

Calories: 939kcal | Carbohydrates: 118g | Protein: 7g | Fat: 51g | Saturated Fat: 31g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 13g | Trans Fat: 2g | Cholesterol: 206mg | Sodium: 446mg | Potassium: 111mg | Fiber: 1g | Sugar: 95g | Vitamin A: 1568IU | Vitamin C: 11mg | Calcium: 42mg | Iron: 1mg