Preheat the oven to 180°C (160°C for fan assisted ovens)/Gas Mark
Grease a 20cm square shallow cake tin and line the base and 2 sides with baking paper.
In a large mixing bowl, stir the brownie mix, oil, 75ml water, and egg together until well blended. Spread the mixture evenly in the prepared tin and bake for 20-25 minutes until a round bladed knife inserted into the brownie comes out almost clean. Transfer to a wire rack and leave to cool completely in the tin; about 30 minutes.
Lift the brownie from the tin using the baking paper. Cut the brownie into 16 squares.
Divide icing into five separate bowls. Stir 1 teaspoon desired food colour into each bowl. Spoon each colour icing into separate decorating bag fitted with desired tip. Pipe frosting on brownies to look like monster’s fur.
Decorate each cupcake as desired using Betty Crocker Vanilla Frosting and food colouring, melted chocolate and sugar eyes.
Icing colours: Orange and green for a Pumpkin, Green for Frankenstein, White for Mummy.