In a copper roasting pan, sear squab in vegetable oil over high heat. Add garlic and transfer to oven and continue roasting until meat is pink.
Cut stem of swiss chard into 3-inch triangles. Bring pot of water to boil. Add celery root and cook until tender. Remove from heat and puree. In another pot, add 1/2 cup creme fraiche and cook until reduced by 25 percent. Add celery root puree. Season with salt, pepper and nutmeg.
In a separate pot of boiling, salted water, add swiss chard triangles and cook until tender. Set aside and keep warm.
In saute pan, add 1 tablespoon butter, onions and mushrooms, saute for 3 minutes. Add remaining 1/2 cup creme fraiche and swiss chard leaves. Cook until reduced and cooked through, about 5 minutes.
Add liver to roasting squab and leave 1 minute.
Remove all from oven, separate legs and breast from carcass, reserve liver. Chop carcass using a French knife and return to stove with bones, garlic and wine. Reduce to 1/3, add stock and simmer 5 minutes longer. Add 1 tablespoon butter and press through in a china cap.
Put dish together by placing puree of celery root in middle of a large plate. Display sliced breast and legs around the puree. Using a round cookie cutter, mound swiss chard leaves and liver in a tower on top of the puree. Place sauce around plate and finish by placing triangles of chard on sauce evenly spaced around the plate.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.