Pre-heat your oven to 160C Fan/350F/Gas Mark 4, and grease and line one 6" cake tin (that is at least 2" deep)
Make the sponge by mixing the butter or baking spread and caster sugar in a large bowl, ideally using an electric mixer for around 3 minutes
Add the eggs and milk, and whisk until fully incorporated
Add the self raising flour, cocoa powder and baking powder and whisk or fold in gently until you can't see any flour anymore
Pour the mixture in the tin and smooth the mixture into an even layer. Bake for 25-30 minutes or until a thin skewer inserted in the middle comes out clean. Leave to fully cool either in the tin or remove from the tin and place on a cooling rack
If you are using shop bought cake
To cut the Easter egg in half, warm a large sharp knife under a hot water tap. Carefully dry it off, then very gently press it around the egg where the seam is. Keep slowly and gently working your way around the egg, re-warming the knife if needed, until the two halves separate
Cut or tear up your cake and fill the Easter egg halves about half full with it
To make the ganache, put the double cream, dark chocolate and butter into a microwave safe bowl. Blast it on high for 20 seconds, then stir well. Blast in 10 second goes, stirring well between each one, until it is smooth and glossy. You can also use a bain marie
Divide the ganache equally between the Easter egg halves and smooth out into an even layer
For the cornflake layer, add the cornflake cereal to a mixing bowl
In a pan on a low heat, melt together the butter and golden syrup
Take the pan off the heat and add the dark chocolate and milk chocolate. Stir until the chocolate is fully melted. If you need to, you can put it back on a very low heat to fully melt the chocolate
Pour the chocolate mix into the cereal and mix together until the cornflake is fully coated
Divide the chocolate cornflake mixture between the Easter egg halves
Decorate with the mini eggs while the chocolate is still wet so that they stick
Store in an airtight container in a cool place, eat within 3-5 days
Notes
I used cornflake cereal for this recipe, but you could also use rice krispies, shredded wheat, or another cereal of your preference.
I used a combination of milk and dark chocolate for the cornflake layer, which I think works really well together. If you want to use all milk or all dark, you absolutely can do. If you wanted to make this with white chocolate, I would recommend omitting the golden syrup as it can make the white chocolate go a unappetising colour.
Golden syrup is sold all over the world, so check the international section in your supermarket if you're not based in the UK. You can also buy it online from Amazon (see link below). If you can't get hold of it, light corn syrup or glucose syrup are the closest things to it, however I've not tested this recipe with them. Please note, you will not get the same results if you omit the golden syrup.
I decorated this recipe with little chocolate eggs for Easter, but you can decorate however you like - or not at all.
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.