Chris Pratt & Katherine Schwarzenegger Look Smitten on Picnic Date

Chris Pratt is apparently a hopeless romantic, who really knows how to make a girl laugh -- just ask Katherine Schwarzenegger!!

Chris was spotted on a picnic date Sunday with Arnold and Maria's 28-year-old daughter. The duo's outing went down up in Santa Barbara, and Chris was a total gentleman -- picking up Katherine at her place and driving her up the coast in his truck ... they even stopped to get gas together.

We've seen Chris get flirty before, but this is the first time we've seen him on a full-fledged date since he filed for divorce from Anna Faris back in December.

While Katherine clearly has a Hollywood pedigree, she's not IN the biz. She's an interior designer and lifestyle blogger.