A smooth and delicious caramel flavoured buttercream icing.
Make the caramel sauce first. Mix the sugar, butter, and milk in a heavy saucepan and whisk together gently over low heat until the butter and sugar melts into a liquid.
Turn the heat up to medium and cook for about 5 minutes until the center bubbles and the mixture begins to thicken.
Put the caramel mixture aside and let cool until it's at room temperature.
Pour the caramel into the stand mixture, and gradually add the powdered sugar to the mixer until it's well mixed and is a creamy and smooth texture.
Once the cupcakes have cooled, pipe the icing onto each of them (or apply with a butter knife for less icing). Garnish each with a slice of green apple and a drizzle of caramel sauce.