Shuck the oysters and drain, saving the oyster liquor for the sauce and the top shells.
In a non-corrosive saucepan, add the oyster liquor, 8 ounces of the heavy cream, the celery seed, bay leaves, parsley, lemon zest, and juice. Bring to a boil and let reduce by 1/8. Strain through a fine sieve and return the cream mixture to the saucepan. Add the finely diced celery and ham and bring to a boil. Add the black pepper and check for saltiness, as the ham will add a great deal of salt to the mixture. If it is too salty, (hams will vary in saltiness) add a little more cream. Keep warm.
Drain the celery root, and, in another saucepan, add the celery root. Cover with fresh, salted water and bring to a boil. Cook until tender and drain. In a food processor, add the celery root, butter, and remaining cream, and puree.
Preheat the broiler. Place a 1/2 teaspoon of the celery root puree into each of the oyster shells, top with an oyster, and spoon the celery ham cream over the oysters. Place the filled oysters on bed of sea salt on a sheet pan and broil in the oven for about 5 minutes or until browning and bubbly. Serve at once.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.