Step 1

Preheat the oven to 350F. Heat the olive oil in a large, heavy-bottomed pot over medium-high heat. Add the beef and onion to the pot. Sauté, breaking the beef into small pieces, until it is completely cooked through. Add the garlic and tomato paste. Cook for 1 minute, stirring to mix the tomato paste into the beef.

Step 2

Add the tomato sauce, crushed tomatoes, and Italian seasoning to the pot, and stir. Bring the sauce to a bubble then reduce the heat to low. Cover the pot with a lid and simmer for 10-15 minutes. Taste for seasoning and add salt and pepper as needed. If the sauce is too thick, stir in a bit of water.

Step 3

Mix the ricotta, parsley, 1/4 cup of the parmesan, and a pinch of each salt and pepper in a bowl. Taste the mixture and adjust the seasoning as needed, then mix in the egg.

Step 4

Spread about 2 cups of the sauce on the bottom of a 9 x 13" casserole dish. Layer: 4-5 lasagna sheets over the sauce, then spread 1/3 of the ricotta mixture over the noodles, top with 2/3 cup mozzarella, then 1 2/3 cups sauce. Repeat those layers, starting with the noodles, twice more. Finish with 4-5 lasagna sheets, the remaining sauce, remaining mozzarella, and remaining 1/2 cup of parmesan cheese.

Step 5

Cover the casserole dish with foil and bake for 45-55 minutes. Use a knife to stab through the middle of the lasagna to test the doneness of the noodles. Once they are tender, remove the foil and bake for another 15 minutes. If you want the top browned even more, turn on the broiler for 1-3 minutes. Let the lasagna rest for 15 minutes before slicing and serving.