Thoroughly grease a 9×13 pan. I lined it with heavy duty aluminum foil and sprayed with cooking spray. This way they just popped right out.
For the bottom layer: Add chocolate chips and peanut butter in a microwave safe dish. Melt them together, stirring after every 30 seconds being careful not to let the chocolate burn. Spread the layer evenly in the bottom of your 9×13 pan. I put each layer in the fridge to let it completely harden. This will help speed up the process because each layer need to be completely cooled and set
For the nougat layer: Melt the butter over medium high heat in saucepan. Add the milk and sugar and bring mixture to a boil. Cook for 5 minutes, whisking together occasionally. Add in marshmallow fluff, peanut butter, and vanilla stirring until smooth. Take the saucepan off of the heat and fold in the peanuts. Pour over the bottom chocolate layer and spread evenly. Allow to cool completely.
For the caramel layer: Melt caramels and heavy whipping cream in microwave, stirring every 30 seconds until smooth. Pour over the nougat layer and allow to cool completely.
For the top chocolate layer: Melt chocolate and peanut butter in the microwave together stirring 30 seconds at a time until smooth. Pour over and spread evenly over the caramel. Cool bars completely in the fridge. Keep them in fridge until right before serving because the bars will soften.