In a large saucepan melt together butter and brown sugar.
Add marshmallows, and stir until melted.
Remove from heat and let sit 1-2 minutes. Add Rice Krispies, and toss until well-coated. Lastly, fold in butterscotch morsels.
Transfer to a well-greased 13x9x2" baking pan, making sure to grease the sides as well.
Pack down with a fork or a spatula until flat and evenly spread. Cover and chill, for at least one hour. Cut into squares and serve.
Submitted by: Dan Mishkin