Looks festive for the holiday season and tastes delicious.
Preheat oven to 350 degrees F. Cook shells on the stovetop, following the package directions. Drain well.
In a mixing bowl, combine cottage cheese, Parmesan cheese, egg, spinach, and pepper. Mix well.
Spread a layer of Marinara sauce on the bottom of a 9 x 13 inch baking dish. Stuff each of the cooked shells with the cottage cheese and spinach mixture. Place them in a single layer on the sauce in the baking dish. Top with the remaining Marinara sauce and the shredded Mozzarella cheese.
Bake until the cheese is melted and the shells are heated through, about 30 minutes.
This recipe may be made with Ricotta cheese instead of cottage cheese for a more authentic Italian flavor, but I like using the low fat cottage cheese and, more often, have it on hand.
Fresh spinach can be used instead of frozen. It's your choice.