TheFork users who ate in Châtenay-Malabry have said really good things about Le M22 Vélizy, Restaurant le Double V - Hôtel Best Western and L'Ermitage. Maybe you should give them a try!
Some of the more popular Restaurant hotel restaurants having a terrace in Châtenay-Malabry according to TheFork users include:
Le Biostrot, with a 9.2 rating
El Bahia, with a 9.2 rating
Les 3 Marches - Brasserie, with a 9.2 rating