Preheat the oven to 350°F and line a 9 x 13 inch baking pan with parchment paper.
Crush 32 Nutter Butter cookies into fine crumbs using a food processor, blender, or a rolling pin inside a sealed bag.
Combine cookie crumbs, brown sugar, and salt in a large bowl. Stir in melted butter until well mixed.
Press the crumb mixture evenly into the prepared pan using a flat-bottomed glass or measuring cup.
Melt 1/4 cup of creamy peanut butter in a microwave-safe bowl for about 30 seconds and stir in the sweetened condensed milk until combined.
Sprinkle peanut butter chips and roasted peanuts evenly over the crust.
Pour the peanut butter and condensed milk mixture over the topped crust.
Add chopped Nutter Butter cookies and Reese's Pieces over the filling.
Gently press the toppings into the filling with a spatula or fork so they adhere well.
Optionally sprinkle flaky sea salt on top.
Bake for 30 to 35 minutes until the edges are golden brown.
Cool the bars on a wire rack and then chill in the refrigerator before serving.
Melt 2 tablespoons creamy peanut butter and drizzle on top of the bars before serving.