Step 1

Heat oven to 350°F.

Step 2

Line 13x9-inch pan with foil, with ends of foil extending over sides; spray with cooking spray. Microwave chocolate and butter in large microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted. Add sugar; mix well. Blend in eggs and vanilla. Stir in flour and nuts; spread into prepared pan.

Step 3

Bake 30 to 35 min. or until toothpick inserted in center comes out with fudgy crumbs. (Do not overbake.) Cool completely.

Step 4

Use foil handles to lift brownies from pan. Cut into heart shapes with 2-inch cookie cutter. Reserve scraps for snacking or other use. Decorate cutouts with frosting and sprinkles.