1 (12 oz.) can corn beef, crumbled
1 lb. sauerkraut, drained
3/4 c. mayonnaise
1 c. Mozzarella cheese, shredded
1/3 c. butter, melted
3 c. rye bread (cubes)
2 tbsp. ketchup
1 c. Cheddar cheese, shredded

Heat oven to 350 degrees. Grease 1 1/2 quart or 2 quart casserole (I use rectangular) and layer the ingredients this order: Corn beef, sauerkraut, mayonnaise mixed with ketchup, Mozzarella cheese, Cheddar cheese, rye bread cubes, and top with melted butter. Cover and bake 30 to 40 minutes. Uncover and bake for 15 minutes or more.