Step 2
Line 8-inch square pan with foil, with ends of foil extending over sides; spray with cooking spray. Microwave chocolate and butter in large microwaveable bowl on HIGH 1-1/2 min. or until butter is melted; stir until chocolate is completely melted and mixture is well blended. Add sugar; mix well. Blend in eggs. Add flour and baking powder; mix well. Stir in nuts.