Pancake cake with mushrooms

Ingredients: 3 eggs, 250 ml. milk, 0.5 tsp sugar, ¼ tsp salt, 300 gr. flour, 100 ml. mineral water, vegetable oil.
Filling: 150 ml. chicken broth, 2 onions, 500 gr. champignons, 3 cloves of garlic, 2 tbsp. tablespoons of butter, 70 gr. cream (20%), 100 gr. hard cheese, 1 tsp sour cream, bread crumbs, 1 bunch of dill, pepper, salt.
Preparation: Whisk the milk, sugar, salt and eggs, gradually adding flour and stirring continuously. Make sure that the dough is homogeneous, without any lumps. Leave the bowl with the dough for half an hour, and then pour in the mineral water. Bake the pancakes and stack them on a platter.
Pancakes are ready, let's start filling. Peel and finely chop the onions, fry them in a pan in butter until golden brown. Then add garlic to the onion, which must first be passed through a garlic press, and washed finely chopped champignons. When the mushrooms begin to secrete liquid, turn up the heat, pour in the chicken broth and simmer until the moisture is completely absorbed. Then add salt, sour cream, pepper, cream and 50 grams of cheese, which must first be grated on a fine grater. Mix everything thoroughly and remove the pan from heat after 3-5 minutes.
Take a baking dish, brush it with butter and lay out one pancake. Spread some of the filling on top of the pancake and cover with the second pancake. In this way alternate the "cakes" and the filling until the cake reaches the height you need. Place the rest of the mushroom sauce on the top pancake and flatten. Sprinkle breadcrumbs on the cake and top with a couple of slices of butter. Place the mold in the oven and bake at 200 degrees for 15 minutes. Wait until the pancake cake with mushrooms has cooled down a little, and serve it to the table.