Rocky Road Brownies

Bahan-bahan (16 porsi)

• 1 cup less 1 tablespoon all-purpose flour
• 1/4 teaspoon baking powder
• 1/4 teaspoon salt
• 4 1/2 tablespoons unsalted butter
• 1/2 cup plus 1 tablespoon unsweetened cocoa powder
• 1 1/4 cups sugar
• 1 large egg
• 2 large egg whites
• 2 teaspoons vanilla extract
• 8 regular-size marshmallows
• 1/3 cup white chocolate chips
• 1/3 cup milk chocolate chips