Brown and crumble the ground beef in a nonstick skillet. Season with salt and pepper.Transfer to a greased 9x13-inch baking dish.
Wipe skillet clean and melt butter over medium heat.Add cabbage and onion and cook 8 to 10 minutes to cook the cabbage down some. Season with salt and pepper. Note: Go easy on the salt since condensed soup has a good amount of sodium.Spread cabbage mixture over ground beef.
In a medium bowl, stir together condensed soup, mayonnaise, and ½ cup of shredded cheddar cheese.Spread over cabbage mixture.
In a medium bowl, stir together Ritz crackers, melted butter and remaining cheddar cheese.Sprinkle mixture on top of casserole.
Bake for 30 minutes.
Notes
If you want to make this casserole spicy, add half a teaspoon of crushed red pepper flakes.