Before we get to my Nana’s recipe for pineapple upside down cake, we have to talk about turnips.  Now is the time to eat turnips, as they are nice and firm, crunchy, and not fibrous.  Almost every booth at the farmers market was selling turnips. I was very impressed with the flavor they imparted to this frittata.  When I was shredding them, they smelled like a potato and a radish at the same time.  My dogs ate some raw chunks, and although at first they were surprised, they came back for more.  There is a sweetness to a really fresh turnip, as well as a hint of the radish. This recipe is really easy, but has some prep time.  You have to peel and…