1In 2-quart saucepan, heat milk, chocolate chips and 1/2 cup granulated sugar to boiling over medium heat, stirring constantly; remove from heat. Stir in 1 tablespoon butter and the vanilla.
2Heat 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.
3Bake about 35 minutes or until edge appears dry and top is cracked. Cool completely in pie plate on cooling rack, about 1 hour (center will sink).
4Spread 1 1/2 cups fudge sauce over pie. Spoon ice cream onto pie, mounding and packing firmly. Freeze at least 4 hours until firm. Heat remaining fudge sauce; serve with pie. Store pie in freezer.