Preheat the oven to 350°F and use nonstick cooking spray to grease a 13x9-inch baking dish.
Unroll one of the packages of crescent rolls and, without separating into separate rolls, use it to line the baking dish.
Bake for 5 minutes.
Meanwhile, cook the beef in a skillet with some salt and black pepper.
When it’s no longer pink, drain off the excess grease and push it to the outsides of the pan.
Add the butter to the middle of the pan and let it melt.
Stir in the onions, along with some more salt and black pepper.
Cook for a couple of minutes, stirring often, combining the meat with the onions.
Add the cabbage and cook for another 5 minutes or until wilted.
Taste and season again if required.
Spread this mixture over the layer of crescent rolls in the baking dish.
Sprinkle the cheese on top.
Add the remaining sheet of crescent rolls (again, don’t separate the rolls) on top.
Bake for about 20 minutes or until golden brown.
Let the casserole rest for 5 minutes, then serve.