Step 1: Heat olive oil in a large skillet or Dutch oven over medium-high heat. Add ground meat and cook, breaking it up with a spoon, until fully browned. Drain off any excess fat.
Step 2: Add diced onion and minced garlic to the skillet. Sauté for 3-5 minutes until the onion is softened and translucent and the garlic is fragrant.
Step 3: Stir in crushed tomatoes, tomato sauce, tomato paste, dried oregano, dried basil, red pepper flakes (if using), salt, and black pepper. Bring the sauce to a simmer, then reduce heat to low, cover, and let it cook for at least 15-20 minutes, allowing flavors to meld. Stir occasionally.
Step 4: While the sauce simmers, prepare the ricotta mixture. In a medium bowl, combine ricotta cheese, 1/2 cup Parmesan cheese, chopped fresh parsley, and a pinch of salt and black pepper. Mix until well combined.
Step 5: Preheat your oven to 375°F (190°C). Spread a thin layer (about 1/2 cup) of the meat sauce on the bottom of a 9x13 inch baking dish.
Step 6: Arrange a single layer of wonton wrappers over the sauce, overlapping them slightly if necessary to cover the bottom of the dish (you'll use about 6-8 wrappers per layer).
Step 7: Spoon about one-third of the ricotta mixture over the wonton wrappers and gently spread it evenly. Top with about 1.5 cups of meat sauce, spreading it to the edges. Sprinkle generously with 1 cup shredded mozzarella cheese.
Step 8: Repeat the layering process twice more: wonton wrappers, ricotta, meat sauce, mozzarella. For the final layer, you should end with a generous coating of meat sauce, topped with the remaining mozzarella and an extra sprinkle of Parmesan cheese.
Step 9: Cover the baking dish loosely with aluminum foil (spray the underside of the foil with non-stick spray to prevent cheese from sticking). Bake for 25 minutes. Then, remove the foil and bake for an additional 15-20 minutes, or until the cheese is melted, bubbly, and lightly golden brown.
Step 10: Let the lasagna rest for 10-15 minutes before serving. This allows the layers to set, making it easier to cut. Garnish with fresh basil or parsley if desired.