This 17th-century conservatory restaurant partway up Petřín has a designer interior with lots of pale Nordic furniture and Singapore orchids, as well as a modern international menu seasoned with a few Czech specialities and cheaper vegetarian options. The views are fabulous, even if the place feels a little touristy.
It's also accessible by footpath (600m to/from the lower funicular station), in case you don't want to take the funicular.