Clean the potatoes and put them to boil a little. Once they soften a bit, take them out, cut them into round slices and arrange in an oven dish.
Add the ham, pitted and chopped olives and feta cheese. Season the gratin with the spices. Put it to bake.
Shortly before it's fully cooked, pour on a mixture of eggs, milk and cheese over it and bake finished. Quick, easy and tasty!