Heat lightly greased Belgian waffle maker.
Microwave chocolate and butter in small microwaveable bowl on HIGH 1 to 1-1/2 min. or until butter is melted. Stir until chocolate is completely melted; set aside.
Mix flour, granulated sugar, baking powder and salt in large bowl. Add milk, sour cream, eggs and vanilla; mix well. Stir in chocolate mixture.
Use batter to make 8 waffles as directed in manufacturer’s directions.
Serve warm topped with berries and powdered sugar.