M&M Cookie "Pie"

INGREDIENTS

10 tbsp

unsalted butter (softened)

1/2 cup

light brown sugar

1/4 cup

granulated sugar

large egg

1 tsp

pure vanilla extract

1 1/2 cups

all purpose flour

1 1/2 tsp

cornstarch

1/4 tsp

baking soda

1/8 tsp

salt

1 cup

M&M's (divided)

4 tbsp

unsalted butter softened

1 1/4 cups

powdered sugar (sifted)

1/2 tsp

pure vanilla extract

1 tbsp

milk, half and half or cream

Food coloring (optional (I used 1 drop of red food coloring))