Wash the potatoes, boil, let cool, cut into slices. Wash the spinach, collapse in boiling water (1 minute), drain, drain well. Clean the mushrooms with a dry cloth, cut into slices. Roughly grate the carrots, cut the onion into small cubes.
Fry the onion in hot olive oil until translucent, add the mushrooms and carrots and fry for about 5 minutes. Stir in the flour and yeast flakes, then deglaze with the milk and vegetable stock. Stir in the cream cheese, season with salt, pepper, chili powder, parsley and oregano.
Brush a baking dish with olive oil. Cover the floor with potato slices like a roof tile. Spread the spinach on top, season with salt, pepper and a little nutmeg. Cover this layer with potatoes again. Spread the mushroom sauce on top, sprinkle with the grated cheese and bake in the oven for 20-25 minutes at 180 ° until the cheese is golden brown.