Marbled Brownies
["2 oz. unsweetened chocolate", "2 1/4 c. flour", "2 tsp. baking powder", "3/4 tsp. salt", "12 Tbsp. unsalted butter", "1 c. granulated sugar", "1 c. light brown sugar", "1 tsp. vanilla extract", "3 eggs"]
["Heat oven to 325\u00b0.", "Butter a 9-inch baking pan. Chop and melt chocolate. Cool."]
["unsweetened chocolate", "flour", "baking powder", "salt", "unsalted butter", "sugar", "light brown sugar", "vanilla extract", "eggs"]