What fruits would you use for the filling at this time of year? The spring, yet not spring weather is making the seasonal thing difficult.
I would probably use some good preserves mixed with juice of half a lemon. That makes a great Crostata, imho. Especially when there are no fruits really "in season."
I agree with June. The traditional Italian crostata I've made since I was a little girl always uses jam or preserves, something not too runny.
As a crostata advocate (I am from the region where that was created and women in my family have been doing it for ages) I second what the girls up here said. Go with a good preserve! If using fruit, do preserve+fruit. My mom usually does apricot jam, apples sautèed in rhum and a bit of sugar and sliced almonds.