Cook shells according to package directions until just al dente. Drain but do not rinse. Meanwhile, mash together all remaining ingredients except sauce and optional cheese. Preheat oven to 350 F. Spread 1/3 of the pasta sauce in the bottom of a 9x13 pan. Stuff shells with filling, then place on top of the sauce in the pan. Cover with remaining sauce (and cheese, if using). Bake on the center rack 25 minutes. I like to heat extra pasta sauce to spread over top just before serving. Cover leftovers and refrigerate up to 4 days, or they can also be frozen.View Nutrition Facts