Children's Chocolate Birthday Cake Recipe (Sheet Cake)

Kids’ chocolate birthday cake

  • Easy

This birthday traybake works brilliantly as a base for any children's birthday cake. It's actually a 'sheet cake', a standard baking treat in Texas. We've added chocolate frosting, but you could personalise it any way you like


This is our go-to recipe when we need to make a children’s birthday cake. It works perfectly every time and is so easy to personalise… go with our chocolate frosting and dust with edible sparkles or extra chocolate chips; or make a completely different topping instead. Vanilla frosting, perhaps? Or some orange-flavoured glacé icing? 

Also check out more indulgent chocolate cake recipes such as our ultimate chocolate fudge cake and chocolate loaf cake. We’ve also got more easy chocolate recipes to make with kids such as rocky road and chocolate brownies, plus try our cornflake tart for a simple family-friendly pud.



  • butter 200g
  • golden caster sugar 200g
  • light muscovado sugar 200g
  • self-raising flour 250g
  • cocoa 5 tbsp
  • baking powder a pinch
  • eggs 2
  • soured cream 125g
  • mini marshmallows 2 handfuls (optional)


  • butter 175g
  • cocoa 3 tbsp, plus more for dusting
  • soured cream 2 tbsp
  • milk chocolate 100g, chopped
  • icing sugar 200g


  • Step 1

    Heat the oven to180C/fan160C/gas4. To make the cake, put the butter, sugars and 250ml water in a pan and heat gently until the butter has melted. Take off the heat and stir in the flour, cocoa, baking powder, eggs and soured cream to a smooth batter, then stir in the marshmallows. Pour into a lined 20 x 30cm baking tray (leave some paper overhanging to help you lift it out) and cook for 25-30 minutes. Cool then lift out.

  • Step 2

    For the frosting, melt the butter and 2tbsp cocoa together and add the soured cream and chocolate. add the icing sugar and stir until smooth, then cool completely. Don’t worry if the butter separates; it’ll come back when you beat it. Once cold, beat with electric beaters until the frosting is paler and fluffier. Spread over the cake and dust with cocoa.

Discover more of our best chocolate cake recipes...

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