First fry the minced meat with salt and pepper until it is crumbly. Then add the diced onions and fry for about 5 minutes. In the meantime, cut the rolls open and place the bases in a baking dish. Spread the minced meat mixture on the rolls and cover with the cheese and the roll tops. Place the casserole dish in the oven and bake at 180 degrees top-bottom heat for about 25 minutes.