Preheat oven to 180 degrees. Season cod fillets with salt and pepper. Brush the bottom of an ovenproof dish with butter. Fill in the fish fillets. Peel shallots and chop finely. Spread evenly around the fish. Add white wine. Cook the fish fillets in the heated oven on the second rack from the bottom for 12 to 15 minutes, depending on their size, basting once or twice with the wine liquid.
In the meantime, remove the skin from the carrots and cut them into very small cubes. Finely dice the celery as well. Turn off the oven. Remove the fish fillets and pour the cooking liquid into a pan with the shallots.
Keep the fish warm in the open oven, covered with foil. Add the carrot and celery cubes to the wine liquid and cook for 5 minutes.
Whip 1 dl of the cream until stiff. Cut the chives into rolls. Add the rest of the whipped cream to the vegetable sauce. Add butter in flakes and add to the slightly boiling sauce. Finally stir in chives and whipped cream.
Season strongly with salt and freshly ground pepper. Spread the sauce evenly over the fish fillets and bring to the table on the spot.
Our tip: Fresh chives are much more aromatic than dried ones!