Preheat your oven to 375°F (190°C).

Bring a large pot of salted water to a boil and cook your lasagna noodles according to package instructions until al dente. Drain and lay them flat on parchment paper to cool.

In a large skillet, heat olive oil over medium-high heat. Sauté chopped yellow onion for about 3-4 minutes until softened, then add ground beef and cook until browned, around 5-7 minutes. Drain excess fat.

Add minced garlic to the skillet, cook for 30 seconds, then pour in marinara sauce, dried Italian seasoning, and chopped parsley. Simmer sauce for 10-15 minutes until thickened.

Blend ricotta cheese and egg until smooth in a mixing bowl. Shred mozzarella cheese in preparation for layering.

In a baking dish, spread 1 cup of meat sauce on the bottom. Layer with 3 lasagna noodles, then ⅓ of the remaining meat sauce, dollops of ricotta mixture, ⅓ of shredded mozzarella, and ⅓ of grated Parmesan. Repeat once more.

For the final layer, add another set of noodles, remaining meat sauce, and top with the rest of the mozzarella and Parmesan. Cover with foil sprayed lightly with cooking spray.

Bake covered for 35 minutes, then remove foil and bake for an additional 10-15 minutes until cheese is bubbly and golden brown.

Let the lasagna rest for 10 minutes before slicing.