Chop the onion finely and fry. When it glass, add minced meat and fry until crumbs. Peel eggplant cut into rings, add salt and leave to drain. When ready, together with diced zucchini added to the mince and fry. Cut the tomatoes into small pieces and add to the stuffing, mix everything and flavored with spices. The butter for the topping is melted, pour the flour and fry until golden and carefully diluted with milk. Yolks are broken and they pour the white sauce. Peel the potatoes and cut into slices. In pot alternately stuffing, potatoes, stuffing. Finally watered with topping and bake in moderate oven for 30-40 minutes.