Preheat oven to 350°F (175°C). Grease a 9x9-inch baking pan and prepare brownie mix according to package instructions. Pour into pan and bake for 30-35 minutes until a toothpick comes out with moist crumbs. Cool completely in the pan.

In a mixing bowl, combine marshmallow fluff with creamy peanut butter. Stir until smooth, microwave for 10-15 seconds if needed, then spread evenly over cooled brownies.

In a microwave-safe bowl, combine caramel bits with milk. Heat in microwave for 30 seconds, stirring until melted and creamy, about 1-1.5 minutes total. Pour over nougat layer.

Sprinkle dry roasted peanuts over the warm caramel layer, pressing down lightly to adhere.

In a microwave-safe bowl, combine chocolate chips with peanut butter. Microwave in 30-second intervals, stirring until melted and smooth. Pour over brownies and spread evenly. Let set at room temperature for at least 1 hour before cutting.