Preheat oven to 350F and line a muffin pan with cupcake liners.
Whisk together flour, baking powder, and salt in a bowl.
In a separate bowl, blend together egg, oil, sugar, and vanilla extract.
Blend the wet mixture into the dry ingredients.
Stir the milk in just until batter is smooth.
Fold in the chopped Twix candies.
Divide the batter into the muffin pan and bake for 20-25 minutes.
Meanwhile, blend together ingredients for the frosting.
Take cupcakes out of the oven and leave to cool before frosting.