Ask her out on a date

She turns to leave as you try desperately to come up with something ANYTHING cool to say.

"I wasn’t planning on playing the hero today, but I’m glad you gave me the opportunity. How about you let me thank YOU by buying you dinner some time?"

Hey that actually wasn't half bad! She turns back to face you and stares into your eyes. You get the sense she sees right into your soul, and you wonder what it looks like down there?