Heaven In A Bowl (Peanut Butter Brownie Trifle) from Mary B.

1 fudge brownie mix (13-inch x 9-inch pan size)

2 packages (13 ounces each) miniature peanut butter cups 
4 cups cold 2% milk 
2 packages (5.1 ounces each) instant vanilla pudding mix
1 cup creamy peanut butter
4 teaspoons vanilla extract
2 cartons (8 ounces each) frozen whipped topping, thawed 

Prepare brownie batter according to package directions. Bake in a greased 13-in. x 9-in. baking pan at 350° for 20-25 minutes or until a toothpick inserted near the center comes out with moist crumbs (do not overbake). Cool on a wire rack; cut into 3/4-in. pieces. Cut peanut butter cups in half; set aside 1/3 cup for garnish. In a large bowl, whisk milk and pudding mixes for 2 minutes (mixture will be thick). Add peanut butter and vanilla; mix well. Fold in 1-1/2 cartons whipped topping. Place a third of the brownies in a 5-qt. glass bowl; top with a third of the remaining peanut butter cups. Spoon a third of the pudding mixture over the top. Repeat layers twice. Cover with remaining whipped topping; garnish with reserved peanut butter cups. Refrigerate until chilled.