• Preheat oven to 375°.
• Cook the shells in boiling salted water for 9 minutes, they should be slightly undercooked. Arrange them in a single layer on a baking pan lined with parchment paper. You will only need about 25 or so shells, but cook extra in case some of them break.

Make the meat sauce:

• While the shells cook, start preparing the meat sauce. Heat the olive oil in a large saute pan. Add the chopped onions and ground beef and season with salt and pepper. Break up the beef and cook until no longer pink.
• Add the minced garlic and sauté for 1 more minute.
• Stir in the tomato sauce, tomato paste, balsamic vinegar, brown sugar, and dry red wine. Bring to a boil, stirring occasionally, and then reduce to a simmer over low heat.

Make the cheese mixture:

• In a medium bowl stir together ricotta, mozzarella, eggs, and pepper.

Assemble the pasta:

• Spray a 9 x 13" casserole dish with non-stick spray. Spread half of the meat sauce evenly in the bottom of the dish.
• Arrange the shells in an even layer on top of the meat sauce.
• To stuff the shells with the cheese mixture you can either use a spoon to gently fill each shell or - add the cheese mixture into a large plastic bag and cut a small opening to pipe the filling in that way.
• Spread the rest of the meat sauce over the tops of the shells.
• Bake in the preheated oven for 20 minutes. Remove from the oven and spread the top with more shredded mozzarella. Bake for another 10 minutes.
• Top with chopped fresh basil if desired and serve warm.