Sounds like a wonderful party already! Since the tart and cheesecake are both rich, we’d choose something light and simple to go with it, and your menu is calling out for something green. We’d choose either the thin green beans known as haricots verts or steamed asparagus, which could be prepared a bit in advance and served at room temperature. Either could be dressed with a little olive oil and lemon or a light vinaigrette.