Cook the potatoes with their skins in water with salt and a bay leaf until they are tender. then strain them well and cut them in slices.
In a frying pan we fry the onion that has been cut in cubes. Add the sausages that have been cut into slices and the zucchini that has been cut into cubes. After a few minutes, add the cream, nutmeg and salt and pepper to taste.
In a baking dish we arrange the cooked potatoes. Add the onion and the sausages, and mix well. Spread some breadcrumbs on top and the ham bacon cut into small pieces. Bake for 20 minutes at 190º, remove the potatoes with the sausages from the oven and serve with some fresh parsley on top.