Spray a 9 x 13-inch pan with non-stick cooking spray. Sprinkle 1 c. peanuts on the bottom of the pan, set aside.
In a large microwave-safe bowl, heat peanut butter chips and butter in 30-second increments on 50% power, stirring after each, until melted.
Stir sweetened condensed milk into the chips and microwave on high power for 1 more minute. Stir until smooth and combined.
Fold the marshmallows into the peanut butter chips mixture until evenly coated. Pour over the peanuts in the pan. Spreading even with a spatula, try not to disturb the peanuts.
Press the remaining 1 c. nuts into the marshmallow mixture. Cover and chill for at least one hour.
Cut into squares.
Notes
You may substitute salted dry-roasted peanuts for the cocktail peanuts if you prefer.
Recipe by Not Just Sunday Dinner at https://notjustsundaydinner.com/homemade-payday-candy/