Remove the mushroom stems, then mince the stems. Reserve.
Over medium heat, add olive oil to a pot, when hot, add the onions, stir for 3 minutes, then add the leeks, the minced mushroom stems, salt, pepper, garlic powder, oregano, and allspice, and stir until the onions are transparent.
Add the tomatoes, and stir until everything is light golden brown.
Add the vegan shredded cheese, and the breadcrumbs, stir to combine and turn off the heat.
Fill the mushrooms with the leeks, tomatoes, and mushroom mixture, cover with more shredded cheese place them in a cooling rack then place the cooling rack on a baking sheet, this way the shrooms won’t be soft and wet.
Bake the stuffed mushrooms in a preheated oven at 200C / 390F for 15 to 20 minutes.
Remove the stuffed mushrooms from the oven, sprinkle some minced fresh parsley on top of the mushrooms and enjoy!