In A Saucepan, Cook The Beef And Onion Until Meat Is No Longer Pink; Drain. Stir In Ketchup, Pickles, Salt, Pepper, Garlic Powder And Hot Pepper Sauce; Heat Through. Stir In Cheese. Place About 1/3 Cupful On Six Buns; Serve Immediately. Cover And Refrigerate Remaining Meat Mixture Until Cool. Fill The Remaining Buns; Wrap Individually In Heavy-Duty Foil And Seal Tightly. Freeze For Up To 3 Months. To Use Frozen Sandwiches: Bake In Foil At 400 Degrees F For 30-35 Minutes Or Until Heated Through.