Peel the potatoes and tomatoes, dip them briefly in hot water. The onions, leeks, garlic cloves, mushrooms and carrots are cut finely, then stewed in butter.
Then add the cut into halves snails. Add broth and wine, add chopped potatoes, peeled tomatoes and bring to a boil.
Boil the snail soup until the potatoes soften and add the cream. Allow to simmer on the stove for 5 minutes and add salt, black pepper and a little nutmeg. Remove from the heat and allow it to cool slightly.
Thicken with the egg yolks beaten with a little vinegar and sprinkle it with crushed parsley.