Ingredients: 1 kg of potatoes. 1 egg. Grated sheep cheese. 1 onion. 1 liter of milk. 1 tablespoon of olive oil. Salt. Pepper. 1 round baking tin. preparation: The bakery potatoes are cut, salted and fried in a pan with olive oil. The onion is cut into very fine julienne strips. Take the mold and make layers of potatoes and onion, then pour the milk. It is placed in the oven preheated to 180 ºC until the potatoes are done, once it is out of the oven, pour the beaten egg on top, stir well and sprinkle with grated cheese to put it back in the oven to gratin.