Please prepare all of your ingredients.
Prepare an 8x8 or 9x9 inch pan with cooking spray and parchment paper. Set aside. I trim the edges of the parment with scissors so the pan fits better into my fridge.
In a saucepan, over medium low heat, pour in sweetened condensed milk and heat until hot but NOT boiling.
Add white chocolate and peanut butter to the pot, stirring frequently until melted and smooth.
Let stand for a few minutes to cool a bit, stirring occasionally.
Stir in 1 cup of chopped peanut butter cups, and only stir once or twice so they do not totally melt.
Pour immediately into your prepared pan.
Top with chopped peanut butter cups and chopped Reese's pieces.
Refrigerate at least 4 hours, remove from pan using parchment to hold on to.
Cut into squares, Serve as desired. Enjoy!