PREPARE and bake brownies in 13×9-inch pan as directed on package.
BEAT pudding mix and milk with whisk for 2 minutes. Add peanut butter and sugar; mix well. Refrigerate until brownies are done.
WITH 3-5 minutes of brownie cooking time left, put chocolate in microwaveable bowl on HIGH for 30 seconds and stir. Repeat in 20 second intervals until chocolate is melted.
ADD COOL WHIP to chocolate and mix well. Let stand 1-2 minutes. Spread peanut butter & pudding mix over brownies.
SPREAD chocolate COOL WHIP mix over pudding. Refrigerate 1 hour. If topping needs to solidify a bit more, freeze for 30 minutes.