Step 1: Lightly grease a 9x13 inch baking dish.
Step 2: Quickly dip each peanut butter cookie into the 1/3 cup milk, just enough to moisten, then arrange a single layer of cookies at the bottom of the prepared dish. You may need to break some cookies to fill gaps.
Step 3: In a large bowl, beat the softened cream cheese, 1/2 cup creamy peanut butter, softened unsalted butter, powdered sugar, and vanilla extract with an electric mixer until smooth and creamy.
Step 4: Gently fold half of the thawed whipped topping into the cream cheese mixture until just combined.
Step 5: Carefully spread the cream cheese mixture evenly over the layer of cookies in the dish.
Step 6: Arrange another single layer of milk-dipped peanut butter cookies over the cream cheese layer.
Step 7: In a separate bowl, mix the remaining 1/2 cup creamy peanut butter with the remaining half of the thawed whipped topping until smooth.
Step 8: Spread the peanut butter whipped topping mixture evenly over the second layer of cookies.
Step 9: Cover the dish with plastic wrap and refrigerate for at least 3 hours, or preferably overnight, to allow the cookies to soften completely and the layers to set.
Step 10: Before serving, garnish with chopped peanuts or mini chocolate chips, if desired. Slice and enjoy!