The kids wanted frosting on their donuts today, so I pulled out the butterscotch chips.
I mixed half a bag of butterscotch chips with 2 tsp of margarine and microwaved them for 45 seconds, stirred, and then zapped them for about 30 seconds more and stirred again. Then I threw a couple cups of powdered sugar and 1/4 c softened margarine into the kitchenaid, added the dough-like butterscotch concoction, and whipped it all together. I added a couple tablespoons of milk to get it to the right consistency, and it was PERFECT frosting.
Made for yummy donuts, too. We frosted them while they were hot, and the frosting set up just like storebought donut frosting does.
I'm sorry I can't post a more accurate recipe. It was a case of "pour some of this, now pour some of that" without any measuring at all.
But it was WELL worth it--really yummy result.