Tart sounds great, as would a quiche. Or a pizza, all of which, I guess, are pretty "tartish" in nature. Away from that, I'd saute the leek and prosciutto with some garlic, make a cream sauce with the goat cheese, and top some long pasta with it. Lots of cracked black pepper over the top....

Thanks for the suggestion. I went with the tart and added some zucchini. It looks pretty good!

A tart would be hard to beat. If you don't feel "tarty," you could make a cream of leek soup and garnish with the proscuitto.