1 1⁄2 lb ground round
1 salt, to taste
1 ground black pepper, to taste
1 large onion, chopped
1 package (16 oz) chopped frozen spinach, thawed and squeezed dry
1 package (8 oz) cream cheese, softened
1⁄2 cup parmesan cheese, grated
1 jumbo egg, beaten
1 package (12 oz) jumbo pasta shells
2 cup tomato sauce
Place ground round in a large skillet over medium high heat and season with salt and black pepper. Cook until browned. Drain meat, reserving 1 tablespoon fat in the pan, and transfer to a large bowl. Add onion to the skillet and saute until translucent, then place in the bowl with the meat. Stir in spinach, cream cheese, parmesan cheese, and salt and pepper, to taste, until thoroughly combined. Let the filling cool, then mix in eggs. The filling can be made up to 1 day in advance and refrigerated until ready to use.
Preheat oven to 350 degrees F (175 degrees C).
Cook pasta shells in boiling salted water until al dente. Drain and set aside until the shells are cool enough to handle. Stuff shells with filling and place in a large baking dish. Pour tomato sauce over the top and cover the dish with foil.
Bake for about 1 hour or until heated through.