Heat oven to 350°F. Spray 9-inch glass pie plate with cooking spray. In medium bowl, beat eggs, 1/4 cup butter and the chocolate with electric mixer on low speed 30 seconds or until smooth. Beat in brown sugar, 1/2 cup granulated sugar and the Bisquick mix until well blended; beat on medium speed 1 minute or until smooth. Pour into pie plate. Sprinkle with nuts.