Cover 3 baking sheets with parchment; spray with cooking spray. Beat cake mix, oil, water and eggsin large bowl with mixer until blended. Drop 1 cup batter into 2 mounds on 1 of the prepared baking sheets, using 1/2 cup batter for each mound and placing mounds 8 inches apart.
Spread each mound of batter into 6-inch round with back of spoon. Repeat with remaining batter on remaining 2 prepared baking sheets.
Bake 12 min. or until tops spring back when gently pressed in centers. Cool completely. Gently run offset spatula under each cake layer to loosen cake from parchment.
Microwave chocolate and 1-1/2 cups COOL WHIP (about half of tub) in microwaveable bowl on HIGH 1-1/2 min.; stir until chocolate is completely melted and mixture is well blended. Cool until thickened. Meanwhile, beat pudding mix and milk in large bowl with whisk 2 min. Fold in remaining COOL WHIP. Refrigerate until ready to use.
Place 1 cake layer on plate; spread with 1/3 of the chocolate mixture. Cover with second cake layer, 1/3 of the pudding mixture and 1/2 cup strawberries.
Repeat layers twice. Refrigerate 2 hours.