This crab, pasta and cheese gratin from Williams Sonoma (recipe here) is like macaroni and cheese for grown-ups. (Though my kids both liked it, too.) It was moderately time-consuming to put together, but so worth it. I'm planning to make it the next time I host a dinner party since the whole thing can be assembled the night before and then popped into the oven before the guests arrive. It also makes for great leftovers the next day.