Pre-heat your oven to 140C Fan/325F/Gas Mark 3, and line a cupcake tin with cupcake cases
For the cupcake sponge, mix together the butter and caster sugar, ideally using an electric mixer, for 5 minutes until smooth and fluffy
Add the eggs and vanilla extract and whisk them in well
Then gently whisk, or fold in, the self raising flour
Divide the mixture between the cupcake cases, and bake them for 25-30 minutes or until a thin skewer inserted in the centre of the cupcakes comes out clean. Put them on a rack to cool completely
For the buttercream, mix the softened butter on it's own for a few minutes. Then add the icing sugar, vanilla and milk, and mix until smooth. You can do this by hand, but an electric hand whisk or stand mixer with paddle attachment will provide the best results. If the buttercream is too stiff, you can add a little more milk
Spread or pipe the buttercream on top of the cupcakes. Decorate however you wish
Store 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 cupcakes and unsalted butter for the buttercream.
I recommend using a good quality vanilla extract, and not an essence. Extract is real vanilla, whereas essence is synthetic.
If you want to use plain or all purpose flour, the general advice is to add 2 teaspoons baking powder (a measuring teaspoon, not the kind you stir your coffee with) per every 200g plain or all purpose flour. So for this recipe you'd need to add 1 + ¾ teaspoons baking powder. Please note, I have not tested this recipe using plain or all purpose flour.
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.