For the casserole with lamb and leeks, first prepare the vegetables. Peel and finely chop the onions and garlic. Wash the leeks well, cut them in half lengthwise and cut them into fine strips. Dice the potatoes.
Dice the feta as well. Grease a baking dish. Whisk the whipped cream and eggs. Preheat the oven to 180 °C.
Heat some olive oil in a pan and brown the potatoes. Add the leeks. Season with salt and pepper.
In another pan, heat the oil and sauté the garlic and onion. Add the lamb mince. Season with marjoram, salt and pepper.
Mix the contents of both pans and knead in breadcrumbs. Put the mixture into the baking dish and pour the egg-whipped cream mixture over it. Then add the butter in flakes and sprinkle the feta on top.
Put the casserole with lamb and leek in the oven and bake for about 30 minutes.