Line a 8x8 baking pan with 2 sheets of parchment paper to create a t for easy removal. Set aside.
In a large saucepan over medium heat add butter, peanut butter and butterscotch chips, stirring frequently. Alternatively combine in a bowl and microwave in 30 second increments, reducing to 15 second increments until melted and combined stirring between.
½ cup salted butter, ¾ cup creamy peanut butter, 2 cups butterscotch chips
Allow mixture to cool 5 minutes.
Using a rubber spatula, fold in miniature marshmallows. Pour into lined pan.
4 cups miniature marshmallows
Refrigerate 1+ hours before cutting into squares and serving.
Notes
Do not use natural peanut butter for best results.VariationsAdd peanuts, candy-coated chocolates like M&M's, Peanut Butter M&M's, or Reese's Pieces or Rice Krispies for a crunch.To StoreCover or place in an airtight container with parchment between layers and refrigerate.