These scotcharoos were made by my mother when I was a kid, and they continue to be a family favorite. They have a wonderful combination of peanut butter, chocolate, and butterscotch with a crispy texture.
1 tablespoon unsalted butter, or as needed
1 ½ cups peanut butter
1 cup light corn syrup
1 cup white sugar
6 cups crisp rice cereal
½ cup semisweet chocolate chips
½ cup butterscotch chips