In a small bowl, combine flour with baking soda, salt, sugar, and pepper. Add oil and rub with fingertips until crumbly. Add cottage cheese and milk, knead the dough (do not knead for a long time), and form a ball out of the dough.
Place the dough in a baking dish. Roll out the dough on a floured work surface. Place the dough in a greased round pan, covering the bottom and sides of the pan. Put the dough in the refrigerator for 20 minutes.
Cooking mushroom and spinach filling. Heat over medium heat with butter. Add onion and sauté for 1-2 minutes. Add the mushrooms cut into slices to the onion and, stirring occasionally, hold on to the fire until the liquid from the mushrooms evaporates completely (6-8 minutes). Add spinach and stir a couple of times and continue cooking. Season with salt and pepper, add nutmeg, stir and remove from heat.
Put the mushroom and spinach filling on the dough. Remove the dough form from the refrigerator. Pour half of the grated cheese on the bottom and smooth. Top with the spinach and mushroom filling and sprinkle with the remaining cheese.
Sprinkle the quiche with mushrooms and spinach with cheese. In a small bowl, beat eggs with milk and pour over the mixture. Place in an oven preheated to 190-200 ° C and bake for 35-40 minutes until golden brown. Cool quiche for 10 minutes before slicing.
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