Place a layer of béchamel sauce on the bottom of a baking dish and put slices of zucchini on it. Put a layer of Bolognese sauce on it and then the potatoes and eggplant. Repeat these steps until you have used all the béchamel sauce, Bolognese sauce, potatoes and vegetables. Finish with béchamel sauce and sheep's cheese. Bake for 45 minutes at 180° C.