Yeah, just ask her if she'd like to go out sometime (not for dinner on the first time, cafe is a good idea), if not, at least you have a good realtionship as you stand. Be like "Hey, I was wondering if your not busy...." or "Do you have plans for the evening?" I wouldn't directly say "I was wondering if we could go out [sometime]" because she may think you are trying to ask her out out, and that could scare her, might be to sudden and abrubt. Oh, and yes, going to the cafe is a "date" if she asks...which she may ask or may think. If you ask her out, she'll get the hint, if you havent directly told her, that you [may] have intimate (meaning next step after "friends") interests in her.
Maybe you two have mutual feelings about persuing a realtionship together, but don't really know if each other would say it directly to each other. If you let this specualtion or afraidness go on too long, you'll definately hit the friend zone, and she may think you are too nice.