Bake: Prepare and bake the fudge brownie mix in a 9x13 pan according to the package instructions. Allow to cool completely, then cut into 1-inch squares.

Mix Pudding: In a large bowl, whisk together the instant pudding mix, cold milk, and vanilla extract for 2 minutes until thick.

Add Flavor: Whisk the creamy peanut butter into the pudding until smooth. Gently fold in 1 ½ cups of the thawed whipped topping.

Layer 1: In a large trifle dish, arrange half of the brownie squares. Top with ⅓ of the halved peanut butter cups.

Layer 2: Spread half of the peanut butter pudding mixture evenly over the brownies, followed by half of the remaining whipped topping.

Repeat: Add the remaining brownies, another ⅓ of the peanut butter cups, the remaining pudding mixture, and the final layer of whipped topping.

Garnish: Sprinkle the last of the peanut butter cups on top.

Chill: Refrigerate for at least 2 hours before serving.