This is a recipe from Russian Orthodox cuisine. The potatoes were mainly prepared in the past by the elderly and traditionally served for the Christian holiday of the Feast of Saints Peter and Paul.
It's best to choose relatively small potatoes of roughly the same size, fresh if possible. The tray in which you'll be baking needs to be relatively small, regardless of the shape. I used a square 8″ (20 cm) glass cooking tray but ceramic or clay ones also work.
Clean and wash the potatoes under running water, put in a pot, add in water to cover them, a pinch of salt and put on the stove to boil. Boiling time needs to be short, about 5 min., remove from the stove, leave to cool, then peel them.
If potatoes are small, cut in half down the middle, if larger cut into quarters.
Smear a tray with part of the butter, add 1/2 the potatoes, crumble the feta cheese on top, lay on the rest of the potatoes. Distribute the butter in pieces between and on top of the potatoes.
Beat the yolks with the milk in a bowl, season with salt and black pepper, pour this mixture over the potatoes. Bake in a preheated 392°F (200 °C) oven for 30-40 min. to a golden color.
Chop the green part of the green onions, sprinkle it over the potatoes and serve hot.
Notes: I've made this recipe many times and have experimented, even adding cheese, various spices, sausages but personally, I find that the classic recipe is the best. It's really simple, uses few products, and will definitely lead your taste buds addicted.