Wash the potatoes thoroughly. Cook with skin in boiling water for about 20 minutes. Peel garlic and chop finely. Clean the mushrooms, if necessary wash and halve them, if necessary quarter them. Heat 1 tablespoon of oil in a saucepan.
Fry the mushrooms until golden brown. Add garlic and fry. Add frozen spinach, cover and simmer for about 10 minutes. Season with salt and pepper.
Pour the potatoes into a sieve, drain and quarter them. Heat 1 tablespoon of oil in a large coated ovenproof pan (with lid). Fry the potatoes until golden brown, turning them over. Add the mushroom mixture.
Grate the Parmesan finely and whisk with eggs, milk, approx. 1⁄2 TL salt and some pepper. Then pour over the potato and vegetable mixture, cover and let it simmer at low heat for about 10 minutes.
In the meantime, preheat the oven grill and bake the stuck tortilla under the hot grill on the middle shelf for 6-8 minutes.