Place the butter and peanut butter chips into a microwave safe bowl and cook in the microwave for one minute; stir until smooth. You may need to microwave another 30 seconds until done.
Stir in sweetened condensed milk.
Add marshmallows and fold in; press into pan. You will want to press pretty good. A lot of my peanuts on the bottom fell off the bars.
Sprinkle with remaining peanuts and press in.
Allow to set up at least one hour before cutting. You can place it in the fridge if you want to speed that up.
Recipe by Mandy's Recipe Box at https://mandysrecipeboxblog.com/marshmallow-peanut-bars/