Brush each celeriac clean under running water
Cut off the root section of each celeriac in one clean cut. Discard the roots.
pre-heat the oven to 320 F (160 C)
Cut the onion, shallot, leek and mushrooms in slices.
Heat up the olive oil in the pan
Glaze the onion, shallot and garlic
Add the leek and mushrooms and sweat the whole mixture
Mix in the vegetable broth and optionally the cream
Heat up until almost at boiling point
Then place the celery roots in the broth and vegetable mixture with the cut side down
Place the pan without a lid in the oven for 75 minutes. (Larger celeriac needs longer up to 2 h)
Stir the sauce a few times to ensure it does not burn
Serve with the pan on the table or make up each plate in the kitchen as you like