HEAT oven to 400°F.
LINE 13x9-inch pan with foil, with ends of foil extending over sides; spray with cooking spray. Combine flour, nuts, sugar, butter and 1/2 cup toffee bits; press onto bottom of prepared pan. Bake 10 min. or until lightly browned. Cool.
BEAT pudding mixes and milk with whisk 2 min.; spread 1-1/2 cups over crust. Add half the COOL WHIP to remaining pudding; whisk until blended. Spread over pudding layer in pan. Top with remaining COOL WHIP; sprinkle with remaining toffee bits.
REFRIGERATE 3 hours or until firm.