My mother loved gratins, and leftover meat and cold cuts always found their way into our pasta, usually along with zucchini or peas. I have made gratins for my family through the years. The gratin can be made ahead, sprinkled with Parmesan, and kept, covered, at room temperature for a few hours or refrigerated for up to a day before it is finished in the oven. If refrigerated, bring back to room temperature and bake on a cookie sheet for about 30 minutes in a 425-degree oven until heated through and lightly browned on top. Do not try to keep the cooked gratin in a warm oven for more than 10 to 15 minutes, or the pasta will swell up in the liquid and become gooey.

My mother loved gratins, and leftover meat and cold cuts always found their way into our pasta, usually along with zucchini or peas. I have made gratins for my family through the years. The gratin can be made ahead, sprinkled with Parmesan, and kept, covered, at room temperature for a few hours or refrigerated for up to a day before it is finished in the oven. If refrigerated, bring back to room temperature and bake on a cookie sheet for about 30 minutes in a 425-degree oven until heated through and lightly browned on top. Do not try to keep the cooked gratin in a warm oven for more than 10 to 15 minutes, or the pasta will swell up in the liquid and become gooey.