1. Preheat the oven and cook the pasta shells. Preheat the oven to 375°F (190°C). Fill a large pot with lightly salted water and bring it to a rolling boil. Add the shells and cook the pasta, uncovered until it is nearly cooked through but still firm to the bite, about 5 minutes. Drain well and rinse with cold water.

2. Make the meat sauce. While the shells are cooking heat a large, deep skillet over medium-high heat. Add the ground beef and onion and cook while breaking the beef up into chunks with a spatula until no longer pink. Drain and discard any excess grease. Stir in the tomato paste, tomato sauce, salt, oregano, and garlic powder. Simmer for 5 minutes. Spread half of the sauce onto the bottom of a 9×13 inch baking dish.

3. Prepare the cheese filling. In a large bowl, beat the eggs. Stir in ricotta cheese, ¾ of the mozzarella cheese, parmesan cheese, parsley, salt, and pepper. Spoon the cheese mixture into the shells and place them into the baking dish. Once all of the shells have been filled, pour the remaining meat sauce over the shells and sprinkle with the remaining mozzarella cheese.

4. Bake until hot and bubbly. Cover and place into the oven. Cook for about 20 minutes and then uncovered and cook for an additional 10 minutes or until the cheese has melted and bubbly and the shells are hot in the center.