Coffee and chocolate chip cupcakes

Ingredients
150g caster sugar
150g butter
140g self-raising flour
, 10g cornflour
3 medium eggs
3 tsp coffee
100g bag of dark chocolate chips
For the icing and decorations
110g butter500g icing sugar
30ml milk2
tsp coffee essenceI
Method
Preheat your oven to 160ºC/320ºF/Gas Mark 3.
Line a 12-hole muffin tin with cupcake cases.
Beat the sugar and butter with an electric mixer for about 5 minutes until light and fluffy.
Sieve the flour and cornflour and mix together in a large bowl.
Add 1 egg, 1/3 of the sieved flours, a splash of milk, and the coffee and beat with the electric mixer until just combined. Repeat until all the ingredients are combined.You can either add the chocolate chips at this stage and fold them into the mixture with a large metal spoon, or add them to the cupcakes when they are in the tin if you want the same amount of chips per cake.
Divide the mixture between the cupcakes cases. If you are adding the chocolate chips at this stage, use about 15 chocolate chips for each cupcake, and stir them into the batter with a dessert spoon. Bake in the oven for 30 minutes or until the cupcakes are golden and springy to the touch.
Remove from the oven and leave in the muffin tin for 10 minutes before placing on a wire rack to cool completely.
Make the buttercream by adding all the ingredients into a large bowl and beating with an electric mixer for about five minutes until smooth and glossy.
When the cakes are cooled completely, spread and smooth the buttercream onto the tops with a small palette knife and decorate with a chocolate decoration.