Soak buns in water. Peel onion, chop. Drain mushroom liquid. Leave some mushrooms for decoration, mince the remaining mushrooms.

Mix forcemeat with onion, mushrooms, parsley, buns and eggs. Adjust with salt and pepper.

Put the forcemeat on the baking tray and bake in oven for 1 hour over 390°F.

Cut the baking into portion pieces and top with tomatoes, mushrooms and basil.