• Preheat the oven to 375°
• Boil the lasagna noodles in water for 4-5 minutes until just under al dente
• Drain the noodles and set on a pan lined with parchment paper. Add parchment paper in between layers so they don't stick together.

Make the meat sauce:

• Heat the olive oil in a medium saucepan. Add the chopped red onion and ground beef and sauté until cooked through and no longer pink. Add the minced garlic and sauté an additional minute.
• Stir in the tomato sauce, tomato paste, balsamic vinegar, brown sugar, red wine, salt, and pepper. Bring to a boil and reduce the heat to low. Simmer for 15 minutes.

For the cheese layer:

• In a medium bowl combine ricotta cheese, 3 cups of shredded mozzarella, chopped spinach, eggs, and pepper and stir to combine.

Assemble the lasagna

• Spray a 9 x 13" baking dish with non-stick cooking spray.
• Add 1 and ½ cup of meat sauce to the bottom of the pan.
• Arrange the lasagna noodles in a single layer on top of the meat sauce. Top with 1 cup of the cheese mixture and another 1 and ½ cup of the meat sauce. Add another layer of noodles, cheese, and sauce. Repeat this once more, ending with the sauce.
• Top with 1 cup of shredded mozzarella. Cover with aluminum foil and bake for 45 minutes. Remove the foil and bake, uncovered, for 15 minutes.
• Serve warm.