Photo: Linda Pugliese, Hector Sanchez; Styling: Heather Chadduck Hillegas, Buffy Hargett Miller
Allow plenty of time to make fillings, and immediately assemble stacks. You can chill the assembled stacks up to 24 hours ahead of time.
Makes 8 servings
1. Prepare Brownies: Preheat oven to 350°. Line bottom and sides of a 13- x 9-inch pan with aluminum foil, allowing 2 to 3 inches to extend over sides; lightly grease foil with cooking spray. Microwave butter and chopped bittersweet chocolate in a large microwave-safe bowl at HIGH 1 1/2 to 2 minutes or just until melted and smooth, stirring every 30 seconds. Whisk in sugar and vanilla. Add eggs, 1 at a time, whisking just until blended after each addition. Stir together flour, baking powder, and salt in a small bowl. Whisk flour mixture into chocolate mixture until blended. Pour mixture into prepared pan.
2. Bake at 350° for 18 to 20 minutes or until a wooden pick inserted in center comes out with a few moist crumbs. Cool completely on a wire rack (about 1 hour). Lift brownies from pan, using foil sides as handles. Cut 8 circles, using a 3-inch round cutter. Reserve scraps for another use.
3. Prepare Milk Chocolate Mousse: Microwave milk chocolate morsels and peanut butter in a small microwave-safe glass bowl at MEDIUM (50% power) 1 1/2 to 2 minutes or until melted and smooth, stirring every 30 seconds. Cool 5 minutes.
4. Beat 1 cup heavy cream at medium speed with an electric mixer until soft peaks form; fold cream into milk chocolate mixture. Chill while making White Chocolate Mousse.
5. Prepare White Chocolate Mousse: Microwave white chocolate morsels and 1/4 cup cream in a small microwave-safe glass bowl at MEDIUM (50% power) 1 1/2 to 2 minutes or until melted and smooth, stirring every 30 seconds. Cool 5 minutes.
6. Beat remaining 1 cup cream at medium speed with an electric mixer until soft peaks form; fold into white chocolate mixture. Chill while preparing foil molds for Step 7.
7. Assemble stacks: Wash and dry paper clips. Cut heavy-duty aluminum foil into 8 (6- x 10-inch) pieces. Fold each piece in half to form a 3- x 10-inch strip. Wrap each strip around a 3-inch-diameter can. (This helps create a smooth curve.) Wrap 1 curved foil strip around each brownie; secure with a large paper clip. Immediately spoon Milk Chocolate Mousse into a zip-top plastic freezer bag. (Do not seal.) Snip 1 corner of bag to make a small hole (about 1/2 inch). Pipe mousse onto brownies, dividing mixture evenly. Use a small spoon to level gently. Repeat procedure with White Chocolate Mousse. Chill 2 hours; remove foil to serve.