Prepare the pan. Coat a 9×13-inch pan with cooking spray.
Make the bottom chocolate layer. Combine 1 cup milk chocolate chips and ¼ cup peanut butter in a microwave-safe bowl. Microwave in two 30-second intervals, stirring after each. If needed, continue in short intervals, stirring until smooth. Spread evenly across the bottom of the prepared pan. Place in the freezer while you prepare the nougat.
1 cup milk chocolate chips, 1/4 cup creamy peanut butter
Make the peanut nougat layer. Melt the butter in a medium saucepan over medium heat. Stir in the sugar and ¼ cup evaporated milk. Bring to a boil, then cook for 3 minutes, stirring constantly. Remove from the heat and immediately stir in the marshmallow creme, ¼ cup peanut butter and vanilla until combined. Stir in the peanuts. Spread evenly over the chilled chocolate layer and return the pan to the freezer.
4 tbsp butter, 1 cup granulated sugar, 1/4 cup evaporated milk, 1 1/2 cups marshmallow creme, 1/4 cup creamy peanut butter, 1 tsp vanilla extract, 1 cup salted peanuts
Make the caramel layer. Combine the caramels and ¼ cup evaporated milk in a small saucepan. Cook over medium-low heat, stirring constantly, until melted and smooth. Spread evenly over the nougat layer. Return the pan to the freezer while you prepare the topping.
14 oz soft caramels, 1/4 cup evaporated milk
Make the top chocolate layer. Combine the remaining 1 cup chocolate chips and ¼ cup peanut butter in a microwave-safe bowl. Microwave in two 30-second intervals, stirring after each. If needed, continue in short intervals, stirring until smooth. Spread evenly over the caramel layer.
1 cup milk chocolate chips, 1/4 cup creamy peanut butter
Chill and slice. Refrigerate for at least 1 hour, or until set throughout. Cut into 24 squares. Keep refrigerated.