Sweet Potato Pound Cake on Design Sponge

INGREDIENTS

1 stick

unsalted butter, at room temperature

1/2 cup

brown sugar

1/2 cup

granulated sugar

1 cup

mashed roasted sweet potato

large eggs, at room temperature

1 1/2 cups

sifted cake flour

1 tsp

baking powder

1/4 tsp

baking soda

1/4 tsp

salt

1/2 tsp

ground cinnamon

1/4 tsp

nutmeg

1 tsp

pure vanilla extract

1/2 stick

butter, unsalted

1 1/4 cups

powdered sugar, sifted

1 tsp

pure vanilla extract

1/4 tsp

ground cinnamon

2 tbsp

milk