Amazing rainbow layered cupcake with frosting

1. Cupcake
Preheat oven to 180°C, line tins with baking paper.
Cream butter, gradually add Natvia (beat until light and creamy).
Add vanilla essence, then add eggs gradually (beat well after each addition).
Sift flour, baking powder and salt together; fold in alternately with the milk.
Separate batter into 4 portions and add respective food colouring to each
Pour into cake tins and bake for 10 minutes or until cooked.
Cut out cake with cookie cutters and assemble with frosting
Frosting
Chill bowl and pour cream in bowl.
Whip at medium high speed until it starts to thicken.
Slow speed down to medium and gradually pour in Natvia
Continue to whisk until soft peaks form.
Add vanilla extract and whisk by hand until frosting is smooth.