Peel the potato and cut into chip size. Wash and clean the vegetables and cut into small pieces (the onions and leek in rings). Heat the oven to 200 degrees.
Grease a large, flat casserole dish (or the oven`s drip pan) with the oil from the glass. Spread the potato on the oil, season with salt, pepper and rosemary. Now place in the preheated oven and cook for about 30 minutes. Then take it out and spread the vegetables on top, season again with salt, pepper and rosemary. Put the whole thing back in the oven for about 20 minutes. Take it out again and sprinkle the cheese over it. Again in the oven until the cheese melts or is browned.