Smith Island Cake 24 tbsp. unsalted butter, melted, plus more for pans 3 1⁄ 2 cups flour, plus more for pans 2 oz. unsweetened chocolate, chopped 2 oz. semisweet chocolate, chopped 6 tbsp. unsalted butter, melted Make the cake: Heat oven to 350°. Butter and flour four 9″ cake pans; set aside.