The unusual flavor of this dish is given by oil with the aroma of truffle, you need quite a bit of it, but the result is impressive.
Wash the celery well, put on a piece of foil, sprinkle with thyme leaves, crushed garlic (take 4 teeth). Drizzle with olive oil mixture. Salt, pepper. Add bay leaf, a piece of butter (take 20 g). Grate the celery well with the mixture.
Wrap in foil, bake at 180 degrees for 1.5-2 hours.
For the sauce, melt the remaining butter and fry the garlic. Add onions and mushrooms. Salt, pepper. Add mustard and cream. Cook until thickened.
Cut the celery into slices, serve with the sauce. Enjoy your meal!