Step 1

Cut the butter (250g) into cubes and then beat on a low speed until soft. Gradually add the icing sugar (500g - you add it gradually to stop it flying everywhere) and beat until fully combined.

Step 2

Add the Baileys (2½ tbsp) a teaspoon at a time, beating in each addition before adding more.

Step 3

Check the consistency of your buttercream. It should be soft and perfect for piping at this point. If it's a little too soft, pop it into the fridge to harden, checking it every few minutes.

Step 4

Decorate your cakes.