Preheat oven to 350°. Put the butter in a 9 x 13 pan and stick the pan in the oven to melt the butter. After the butter is melted, move the pan so the butter is even distributed. Then sprinkle on the graham crackers crumbs evenly over the melted butter then press down on them to form an even layer.
Evenly sprinkle with the chocolate chips, then butterscotch chips then the mini marshmallows. Pour condensed milk evenly over the mixture.
Bake 25 minutes or until bubbly. Cool. For easier cutting, refrigerate 1 hour.