First slice the onions not too thinly, transfer them to the pan with oil and add salt. Put the lid on and stew over a moderate heat for about 15-20 minutes, at the end of cooking the onions should be softened but not completely cooked.

Now cut the potatoes into slices about 2 mm thick, you can help with a mandoline to do this.

Butter a baking dish about 23-24 cm in diameter, 4 cm high and sprinkle the base and edges with breadcrumbs.

Distribute the slices of potato, salted and seasoned with ground pepper, then form a layer with the stewed onions, add a little crumbled feta and a few fillets of chopped anchovy. Make another layer with potatoes, salted, peppered and continue alternating the ingredients until they are exhausted. The last layer will have to be potatoes.

In a container mix with the eggs the grated Parmesan cheese and milk, add a pinch of salt and a minced pepper, then pour the mixture into the baking dish.

Cover the baking dish with a sheet of foil and place it on a baking tray, this is not to risk dirtying the oven during cooking in case the egg, swelling, comes out of the mold. Wait about 10 minutes before baking so that the egg-based mixture can be distributed in the baking dish homogeneously.

Cook the potato cake in a preheated static oven at 190°C for 45-50 minutes, then remove the foil and continue for 10-15 minutes. If necessary, use the grill function to achieve a beautiful gilding.

Once the potatoes are well cooked, let it cool for at least about ten minutes before serving.

Servite!