Add one can of sweetened condensed milk to a saucepan with 1/2 bag of chocolate chips and 1/2 bag of butterscotch chips. Melt together over low-medium heat. Stir well while cooking, add 1 tsp. vanilla and chopped nuts if desired. Turn out into a buttered 8x8 or so baking dish. Let set or refrigerate for an hour or two. Cut into small pieces--it is very rich. Freezes well for later use. Easy!