From Cooking Light. I've upped the fat a little by using real butter, the recipe originally called for reduced-calorie stick margarine, so you can go that way if you prefer. If you can't find mostaccioli, any tubular pasta will do, like a penne. I can find mostaccioli easier than I can spell it. I usually melt the bit of butter at the end for making the topping; your choice, you can cut it in. Hope you enjoy!