The restaurant is inside "Chateau de Chantilly". Its an interesting experience to eat here. Its a cozy and is decorated as a French countryside restaurant.
Favorite Dish: The salas dishes and fish. Cod was excellent.
I had my Sunday lunch in the main restaurant at the racecourse, with (as you've guessed from the name) a view of the course to the front and parade ring to the rear.
I didn't book in advance, but you should for busier meetings and/or to get a window table.
Not cheap (even just after the French government cut vat on restaurant meals to 5.5%) but very pleasant. Cost €39.10 for 2 courses + water.
It has a betting desk in the restaurant, so you can place your bets (maybe even collect the winnings) between courses.
The same company runs the restaurant inside the chateau.
Favorite Dish: Strawberries with fresh cream and - of course - creme Chantilly.