The Best Gluten-Free Lasagna

Make the sauce: Heat olive oil in a Dutch oven or large pot over medium heat. Add the ground beef, ground sausage, and garlic, and cook until well browned. Stir in the onion, mushrooms, crushed tomatoes, fire-roasted tomatoes, tomato paste, and water. Season with basil, fennel seeds, Italian seasoning, salt, pepper, and parsley. Cover and simmer for about 45 minutes, stirring occasionally.
Prepare the ricotta mixture: In a mixing bowl, combine ricotta cheese with egg, parsley, and ½ teaspoon salt. Set aside.
Preheat oven: Preheat your oven to 375°F (190°C).
Assemble lasagna: Spread 3 cups of the meat sauce into the bottom of a large baking dish (see notes for baking dish size). Top with a layer of lasagna noodles. Spread half of the ricotta mixture over the noodles, then layer with half of the mozzarella slices. Spoon 2 cups of meat sauce over the mozzarella, and sprinkle with ½ cup of Parmigiano. Repeat the layers—noodles, ricotta, mozzarella, and sauce—and finish with the remaining Parmigiano on top.
Bake lasagna: Cover the lasagna with foil. To prevent sticking, tent the foil slightly so it doesn’t touch the cheese. Bake for 25 minutes. Remove the foil and bake for an additional 25 minutes, or hot and bubbling, the noodles are tender, and you get those golden, crispy lasagna corners! Let rest for 10 minutes before serving.