I’ve used leeks and goat cheese here-a classic pairing and very appropriate for Spring. Mix it up and try different cheeses and veggies. Any cheese with good melting properties would be fabulous. You can leave out the cream cheese entirely. Add roasted root veggies or tomatoes. Throw some arugula or baby greens on top of the baked tart. Sprinkle with a little bacon or other cured meats.