Heat oven to 375°F. Separate dough into 4 rectangles. Place on ungreased cookie sheet. Press each to 7x5 inches, firmly pressing perforations to seal.
Spread 1 tablespoon mayonnaise and 1 teaspoon mustard on each rectangle to within 1/2 inch of edges. Place one-half piece cheese in center of each rectangle; top with diced ham and another cheese half. Bring ends up over filling, overlapping about 1 inch. Press edges with fork to seal. Place one-half piece cheese on top of each sandwich.
Bake 13 to 15 minutes or until golden brown. Immediately remove from cookie sheet. Serve warm.