Peel the shallots and garlic, clean the mushrooms, wash the leek. Cut the white of the leek into strips, chop the onions, mushrooms and garlic.
Melt the butter in a saucepan, add the chopped vegetables and mushrooms and simmer for about 5 minutes over a medium heat while stirring. Put the tinned snails in a sieve to drain (collect the stock), then roughly chop. Finely chop the washed parsley.
Add the snails and parsley to the saucepan with the vegetables. Let everything simmer for another 2 minutes in the open pot. Add snail stock, white wine, sweet cream, meat stock extract and water. Salt and pepper the soup and simmer gently for 5 minutes. Thicken the soup with instant white sauce. Then season with Worcestershire sauce, lemon juice, brandy and season with salt and pepper.
With a hood: Pour the finished soup into cups. Mix the cream with the egg yolk, add to the soup, sprinkle with cheese and briefly bake in the grill.