There are no restaurants at the castle but I recommend several good restaurants, gourmet or bistros, all located near Châlons en Champagne, about 10 km from here.
The ""Jerome Feck"" restaurant, gastronomic:
19 Place Monseigneur Tissier, 51000 Châlons en Champagne
www.hotel-dangleterre.fr
+33 3 26 68 21 51 
The bistro ""Les Temps Changent""
19 Place Mgr Tissier, 51000 Châlons-en-Champagne
https://www.hotel-dangleterre.fr/fr/carte-bistrot-les-temps-changent/
+33 3 26 68 21 51 
The restaurant ""Au Carillon Gourmand"":
15 bis Place Monseigneur Tissier, 51000 Châlons-en-Champagne
www.carillongourmand.com
+33 3 26 64 45 07
The ""Le Petit Pasteur"" bistro:
42 Rue Pasteur, 51000 Châlons-en-Champagne
www.restaurant-lepetitpasteur.com
+33 3 26 68 24 78
The restaurant ""Les Sarments"":
15 Place de la République, 51000 Châlons-en-Champagne
+33 3 26 68 16 75
To taste champagne, you can go to this dining cellar:
"At 36...":
37 Rue Dom Pérignon, 51160 Hautvillers
www.au36.net
+33 3 26 52 17 40 