In a large saucepan over medium-high heat, cook the beef, sausage, and onion, stirring often, until browned, about 5 minutes. If there is a lot of grease in the pan, drain it before continuing.

Stir in the garlic, salt, and Italian seasoning and cook for 1 minute.

Stir in the sauce and water. Reduce the heat to medium-low and let simmer for 10 to 15 minutes for the flavors to come together. Remove from the heat to cool slightly.

In a medium bowl, stir together the ricotta, spinach, Parmesan, cream, egg, and 1 cup of the mozzarella. Set aside.

Preheat the oven to 350°F. Lightly grease a deep 9×13" pan.

Spread just enough meat sauce in the bottom of the pan to create a thin layer.

Top with 3 lasagna noodles. Spread the noodles with ⅓ of the ricotta mixture, and top that with ¼ of the meat sauce.

Repeat the layers 3 times, and on the 4th layer of noodles, spread only the remaining ¼ of the meat sauce.

Lightly grease a piece of foil or oven-safe lid and place it over top of the lasagna. Bake for 40 to 45 minutes, until the noodles are tender. (This can take up to 60 minutes, depending on your brand of pasta. It may still be juicy at this point, and that’s okay.)

Uncover and sprinkle with the remaining 2 cups mozzarella. Bake for 10 minutes, until the mozzarella has melted, and broil for 2 minutes if desired to brown the top.

Remove from the oven and let rest for 10 to 15 minutes. (There should not be any liquid remaining on the edges after this rest.) Slice and serve.