Spread 2 cups peanuts onto an 11 x 7 cookie sheet or a 13 x 9 baking dish. Reserve the remaining 1/2 cup peanuts.
Combine the butter, peanut butter chips and chocolate chips in a medium saucepan. Melt over low heat, stirring frequently. Stir in the sweetened, condensed milk and the mini marshmallows until completely melted and smooth.
Pour the chocolate mixture evenly over the peanuts. Sprinkle the remaining 1/2 cup of peanuts on top. Chill the peanut squares in a refrigerator until firm. Sprinkle the sea salt on top.
Cut into small squares end enjoy!
Notes
If you’re not a fan of overly salty sweets, or if you don’t have any coarse sea salt on hand, you can omit the sea salt if you want. However, I think it really adds something special and ties the flavors together nicely!