Ham and Cheese Puff

2 loaves (1 pound each) Italian bread, cut into 1-inch cubes
6 cups cubed fully cooked ham
1-1/2 pounds Monterey Jack or Muenster cheese, cubed
1 medium onion, chopped
1/4 cup butter or margarine
16 eggs
7 cups milk
1/2 cup prepared mustard

Toss bread, ham and cheese; divide between two greased 13-in. x 9-in. x 2-in. baking dishes. In a skillet, saute onion in butter until tender; transfer to a bowl.

Add eggs, milk and mustard; mix well. Pour over bread mixture. Cover and refrigerate overnight. Remove from the refrigerator 30 minutes before baking.

Bake, uncovered, at 350 degrees for 55-65 minutes or until a knife inserted near the center comes out clean. Serve immediately. Makes 24-30 servings.