- Heat oven to 330degF/300degF (fan forced at 150degC). Use baking/grease-proof paper to line and grease an 18cm/7inch spring form pan.
- Beat castor sugar with eggs in an electric mixer for 8-10 minutes until creamy and pale.
- Sift the cornflour and self-raising powder together three times in a separate bowl. Then, sift the flour on top of the egg mixture and fold quickly with a spatula to ensure that all ingredients are combined.
- Melt Copha until completely melted in the microwave or saucepan. Microwave milk (on high, for 20 seconds). Pour Copha, milk, and egg mix down the bowl side and fold it through.
- Pour the final mixture into the prepared pan. Smooth out the surface. Bake for 30 minutes or until a wooden skewer inserted in the middle comes out clean. Remove the pan from the oven.
- Cool cake in pan for 5-10 mins before turning it onto a wire rack to cool for 30 mins.
- Mix sugar and butter using an electric mixer. Mix at low speed for a few minutes until the butter and sugar are well combined. Increase speed to medium and continue beating for three more minutes.
- Continue to beat at medium speed, adding cream as needed.
- Cut your cake horizontally. Be sure to cut it as evenly as you can. Place the bottom layer of the sponge on a plate.
- Spread vanilla frosting on the base. Top the cake layer with your filling layer.
- Spread the frosting evenly over the sides and the top of the cake
- Separate M&Ms according to color. Place one row of M&Ms in alternating colors around the base. As shown in the picture, continue to place M&Ms up the sides of the cake. Continue the same process on the top and sides of the cake once the sides have been completed.
- Before serving, let the frosting set.