Boil the potatoes. Once they cool, leave them in the fridge for a few hours to harden.
Smear an oven dish with a little oil. Grate the potatoes, enough to cover the oven dish, then grate on feta cheese and potatoes once more.
Put the oven dish in a preheated 356°F (180 °C) oven.
While it's in the oven, combine the eggs and milk.
Once the dish is slightly crisped, pour the mixture over it and leave it for 5 min. in the oven.
Next, grate the cheese on top and leave it to bake another 5-10 min. until the cheese gains a crispy, golden color.