– 1 1/2 c. (3 sticks) butter – 3 c. sugar – 2 1/4 c. cocoa powder – 1/2 tsp. salt – 1 1/2 tsp. vanilla – 4 eggs – 1 1/4 c. flour – 1/2 tsp. baking powder – 1 1/4 c. white chocolate chips – Topping: – 2 1/2 c. dark or semi-sweet chocolate chips, melted – 1 c. white chocolate chips, melted