PREHEAT oven to 350°F. Microwave butter and chocolate in large microwaveable bowl on HIGH 2 min. or until butter is melted; stir until chocolate is completely melted. Stir in sugar. Blend in eggs and vanilla. Add flour; stir until well blended. Spread into greased 12-inch pizza pan.
BAKE 25 to 30 min. or until toothpick inserted in centre comes out with fudgy crumbs. (Do not overbake.) Cool in pan on wire rack.
POUR milk into medium bowl. Add dry pudding mix; beat with wire whisk 2 min. or until well blended. Spread over brownies to within 1 inch of edge; sprinkle with crushed cookies. Cut into 16 wedges to serve. Store in refrigerator.