Fruity Pebbles Funfetti Cake

INGREDIENTS

1 1/2 cups

unsalted butter, at room temperature

2 1/4 cups

sugar

large egg whites, at room temperature

2 tbsp

clear imitation vanilla

6 tbsp

vegetable oil

3 3/4 cups

cake flour (see headnote)

3 1/2 tsp

baking powder

1 tsp

salt

1 1/2 cups

whole milk, at room temperature

3 cups

Fruity Pebbles cereal

2 cups

butter, at room temperature

1 tbsp

clear imitation vanilla

3 tbsp

milk or cream

4 cups

powdered sugar