Preheat your oven to 375°F. Lightly grease a 9x13-inch baking dish.
In a large pot of generously salted water, cook lasagna noodles according to package instructions until just al dente. Drain and set aside.
While your noodles cook, heat oil over medium-high heat. Add ground beef and cook until browned. If your meat released a lot of fat while it cooked, drain or spoon off the fat.
Add pasta sauce and simmer until beef is cooked through. Taste and add salt and pepper as needed.
In a medium bowl, whisk together ricotta cheese, egg, 1/2 teaspoon of salt, and 1/4 teaspoon of pepper. Set aside.
Use a ladle to spoon 1/4 of the sauce into your baking dish. Lay 3 noodles lengthwise and top with 1/4 of the sauce. Drop 1/2 of the ricotta mixture over the top in dollops and then gently spread it out into a smooth layer. Sprinkle with 1/3 of the mozzarella and parmesan.
Lay another layer of noodles, this time using 4 and placing across the dish instead of lengthwise, trimming the edges as needed. Add the sauce, remaining ricotta, and cheese just as you did with the last layer.
Add final layer of noodles, going horizontally this time and top with remaining sauce and cheese.
Cover tightly with foil and bake for 35 minutes. Remove foil and continue to bake until cheese is melted and the lasagna is hot all the way through, about 15 minutes.
Let the lasagna sit for at least 10 to 15 minutes before cutting and serving. Serve and enjoy!