Preheat oven to 350°F. Coat a 9 x 13 inch baking dish with nonstick cooking spray.
Cook pasta shells according to package directions until al dente. Drain and set aside to cool.
In a large bowl, combine ricotta cheese, 2 cups mozzarella cheese, 1/2 cup parmesan cheese, eggs, parsley, minced garlic, salt, and pepper. Mix well until thoroughly combined.
Spread 1 cup of spaghetti sauce evenly over the bottom of the prepared baking dish.
Transfer ricotta mixture to a pastry bag or large resealable plastic bag. Snip off one corner of the bag.
Squeeze approximately 1 tablespoon of cheese mixture into each cooked shell. Place filled shells in the baking dish.
Pour remaining spaghetti sauce over the filled shells, ensuring they are well covered.
Cover tightly with aluminum foil and bake for 40 minutes.
Remove foil and sprinkle remaining 1 cup mozzarella cheese and 2 tablespoons parmesan cheese over the top.
Bake uncovered for 10-12 minutes more, until cheese is golden and bubbling.
Let stand for 10 minutes before serving to allow filling to set.