Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line a 12" x 9" traybake tin
Make the cake by mixing the baking spread and caster sugar in a large mixing bowl until fluffy, about 2-3 minutes, ideally using an electric mixer
Add the eggs, milk and vanilla extract, and whisk until fully incorporated
Gently whisk or fold in the self raising flour
Pour the mixture into the tin, spread it out into an even layer
Bake for 25-30 minutes or until a skewer inserted in the centre comes out clean. Leave to cool fully either in the tin or on a cooling rack
To make the buttercream, mix the butter in an electric mixer with the paddle attachment for a few minutes. Add the icing sugar, milk and vanilla extract and mix until well combined and smooth
Spread or pipe the buttercream all over the cake
To serve, decorate as you prefer, then slice into squares. Store any leftovers in an airtight container in a cool place and eat within 3 days
Video
Notes
Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
I used a baking spread for the cake and unsalted butter for the buttercream.
For the best flavour, make sure to use a good quality vanilla extract and not an essence. You can also use a vanilla bean paste.
You will need a 12" x 9" traybake tin for this recipe. However, if you want to make it in a 9" square tin, check the recipe notes for the measurement details.
You can decorate this cake with anything you like! If it is for someone's birthday, perhaps their favourite chocolates on top. Fresh strawberries or raspberries would also look fabulous!
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.
If you want to make this cake in a 9" square tin you will need: