Apple-Ham Grilled Cheese

1 c. chopped tart apples
1/3 c. mayonnaise
1/4 c. finely chopped walnuts
8 slices process American cheese
8 slices sourdough bread
4 slices fully cooked ham
1/4 c. butter, softened

In bowl combine apples, mayonnaise and walnuts. Place a slice of cheese on four slices of bread. Layer each with 1/3 cup of apple mixture, a slice of ham and another slice of cheese; cover with remaining bread. Butter outsides of sandwiches. In large skillet over medium heat cook sandwiches until each side is golden brown and cheese is melted. Makes four servings.