Line the bottom of an 11-inch by 7-inch baking pan with parchment paper or wax paper.
In a small bowl, combine 1 cup chocolate chips and 3 tablespoons peanut butter. Microwave for 60 seconds at full power and stir to combine. Microwave a few more seconds if needed, until the chocolate is melted and smooth.
Pour chocolate mixture into prepared pan and spread evenly. Freeze until the chocolate is hard, about 2 to 3 minutes.
For Nougat Layer:
In a medium sized bowl, combine marshmallow fluff, ¼ cup peanut butter, and 1 ½ cups powdered sugar. Using a wooden spoon or strong spatula, stir until a soft nougat dough ball forms.
Remove nougat dough from the bowl and press on top of hardened chocolate layer. Sprinkle 1 cup peanuts on top of nougat and gently press them down.
For Caramel Layer:
In a small saucepan over medium heat, combine caramels and ¼ cup heavy cream. Stir constantly until caramels have melted and cream is incorporated.
Pour immediately over the peanut layer, using the back of a spoon to spread evenly. Refrigerate until caramel has set, about 5 minutes.
For Chocolate Layer:
In a small bowl, combine the remaining 1 cup chocolate chips and 3 tablespoons peanut butter. Microwave for 60 seconds at full power and stir to combine. Microwave a few more seconds if needed, until the chocolate is melted and smooth.
Pour chocolate mixture over caramel layer and spread evenly. Refrigerate until chocolate layer has hardened, about 10 minutes. Using a sharp knife, cut into 12 bars and serve.