COVER bottom of 9-inch square pan with cake slices, cutting and piecing slices to fit. Beat pudding mixes and milk with whisk 2 min. (Pudding will be thick.) Stir in 1 cup COOL WHIP; spread over cake slices.
REFRIGERATE 2 hours or until firm.
TOP with remaining COOL WHIP and berries just before serving. Drizzle with syrup.