Clean the mushroom and cut the legs out. I don't peel them, but if you do so, you can :-)

Cut the mushroom legs into small cubes, onion cut finely as well. Heat the owen for 200°C. Boil the potatoes.

Heat up 2 spoons of oil in pan. Now add onion with cutted mushroom and stir fry for 5 minutes.  Then strew the spinach in pan also and fry until the spinach is melted well. It takes about 10 minutes. Finish with salt and pepper.

Put the mushroom top's in the baking pan. Fill them with spinach mass.

Now you just need to grate the vegan cheese finely and mix it with cutted parsley. Resulting mixture just put on top of the spinach.

Bake in preheated owen for 20 minutes.