Briefly fry the onions cut into rings in hot olive oil. Then add the minced meat and fry until crumbly. Peel and slice the potatoes. Let it simmer for a few minutes. Cut the zucchini into slices and the leek into rings and sauté briefly. Then add the cream and milk, bring to the boil. Season to taste with the spices. Then fill a baking dish and top with sliced mozzarella. Bake at about 200 ° C for about 20-30 minutes, until the cheese is nice and brown.