Step 1

Thoroughly clean the potatoes, dry them, wrap them in aluminum foil and bake them at 350°F for about 1 hour. Check that they're done with a toothpick before you remove them from the oven. Clean the champignon mushrooms and cut them in half. Sauté them in a pan with some foamy butter until they have browned well.

Step 2

Remove the potatoes from the foil. Cut off the top of the potatoes (on the long side), scoop them out and fill them with the egg white while still piping hot. Lightly salt and put them back in the oven at

Step 3

350°F for a few minutes, keeping an eye on them. Once the whites have completely cooked, remove them from the oven and complete with the egg yolk, a few leaves of thyme, flakes of salt, freshly ground pepper and black truffle slivers. Serve immediately with the browned mushrooms on the side.