Begin by preheating your oven to 375°F (190°C) to ensure it's hot and ready for your delicious lasagna.
Cook the lasagna noodles according to the package instructions until they are al dente. Once cooked, drain them thoroughly and set aside.
In a large skillet over medium heat, pour in the olive oil. Add the finely chopped onion and minced garlic, sautéing them together until the onion becomes soft and translucent, about 3-5 minutes.
Next, incorporate the ground beef (or plant-based substitute) into the skillet. Cook this mixture, breaking it up with a spatula, until the meat is browned. If there's any excess fat, drain it from the skillet.
Stir in the crushed tomatoes along with the dried basil, dried oregano, salt, and pepper. Allow the sauce to simmer for approximately 10-15 minutes so that all the flavors can blend beautifully.
In a separate mixing bowl, combine the ricotta cheese, beaten egg, and half of the grated Parmesan cheese. Mix until smooth and well incorporated.
Now, you’re ready to layer your lasagna! In a generously greased baking dish, start by spreading a thin layer of the meat sauce on the bottom. Place 3 lasagna noodles on top, and follow with a layer of the ricotta mixture, a sprinkle of shredded mozzarella cheese, and another layer of meat sauce. Repeat this layering process until all ingredients are used, remembering to finish with a layer of meat sauce on top.
Add the remaining mozzarella cheese and Parmesan cheese generously over the final layer of meat sauce, creating a deliciously cheesy topping.
Cover the dish tightly with aluminum foil. To prevent the foil from sticking to the cheese, lightly spray the inside with cooking spray before covering.
Place the lasagna in the preheated oven and bake for 25 minutes. After this time, remove the foil and continue baking for an additional 15-20 minutes, or until the cheese is bubbling and beautifully golden brown.
Once out of the oven, let the lasagna rest for about 10 minutes to settle and make slicing easier. Just before serving, garnish with fresh basil leaves for a pop of color and flavor.