HEAT oven to 325°F.
MICROWAVE chocolate and butter in small microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted. Add sugar, eggs and vanilla; mix well. Stir in flour. Spread onto bottom of 9-inch pie plate sprayed with cooking spray.
BAKE 30 to 35 min. or until toothpick inserted in center comes out with fudgy crumbs. (Do not overbake.) Use back of large spoon to make slight depression in center of brownie. Cool completely.
BEAT pudding mixes and milk with whisk 2 min. Let stand 2 min. Spread over brownie.