Bring A Large Pot Of Lightly Salted Water To A Boil. Add Pasta And Cook For 8 To 10 Minutes Or Until Al Dente; Drain. In A Large Saute Pan, Melt Butter And Saute Onions And Garlic Until Onions Are Almost Translucent. Stir In Flour, Coating All Of The Onions Well. Gradually Pour In Milk, Stirring Constantly. Stir In Mushroom Soup And Seafood. Cook For 10 Minutes Or Until Shrimp Are Pink And Scallops Are Opaque. Serve Over Pasta.