Peel the potatoes and put them in a large pot filled with water. Boil them until they're tender. Mash them and let them cool for a while.
Chop the mushrooms, carrot and red bell pepper. Add them into your food processor and pulse until all ingredients are well mixed together.
Heat 2 tbsp of sunflower oil in a large skillet. Add the mixture above, diced onions, chopped dill and parsley, soy granules, eggs ( or egg substitutes + dry yeast flakes) and spices. Sauté for 10 minutes.
* I added the soy granules without boiling them because the mushrooms contain a lot of water and these soy granules will absorb all excess water.
Put some parchment paper on the bottom of a casserole. Divide the mashed potatoes in two. Place the first half in the casserole and spread it with a spatula. Add the filling. Place over the other half of mashed potatoes.
Heat your oven at 392˚. Put the casserole in the oven. Cook for 40 minutes.
Don't serve immediately. Let it cool for at least half an hour.