Preheat A Skillet Over Medium-High Heat. Spread One Side Of Each Slice Of Bread With 1 Teaspoon Butter. Place One Slice, Butter-Side Down In The Hot Skillet. Top With Swiss Cheese And Ham. Spread The Unbuttered Side Of The Second Slice Of Bread With Mayonnaise And Mustard; Place It, Butter-Side Up On Top Of The Sandwich. Cook Until The Sandwich Is Golden Brown And The Cheese Is Melted, About 3 Minutes Per Side.