What kind of cabbage do you have?
If you have a green/white cabbage:
Boil/steam cabbage till it's just tender
Fry a thinly sliced onion
Mix cabbage with onion and put into a casserole dish; season with salt and black pepper
Pour over a tin of chopped tomatoes
Cover the top with a generous amount of grated cheese and bake for about 20 minutes until the cheese is nice and brown on top
If you have a savoy cabbage:
Make some kind of meat stuffing (I use finely chopped boneless pork chops, onion, mushroom and any other interesting veg I happen to have - but use veg that doesn't require much cooking - carrots/potatoes will need to be cooked first)
Take off the leaves of your cabbage gently, so that you don't tear them. Cut out the centre/tough stalks, then blanch them in boiling water for a couple of minutes. Drain.
When they are cool enough to handle, take each leaf, dollop some of the meat filling in them, roll them up and put them seam side down in a casserole dish.
Cover the stuffed cabbage in either a cheese sauce or a tin of chopped tomatoes, then sprinkle a generous handful of grated cheese on top and bake in the oven for about 20 minutes.