I don't know what authentic Fountain Hills food would be but I recommend DJ's Bagel Cafe and Phil's Place and it's located at 16758 E. Glenbrook Blvd. Copper Wynd/Alchemy is pretty good too and it has an AMAZING view. Scottsdale Wine Bar Fine Dining
Have a good time. It is a really cool little town. I lived there for a couple of years in the early 2000's. I still live in the Phoenix area. If you want any other recommendations send me a pm.