In a large saucepan or Dutch oven over medium-high heat, add beef (or sausage) and onion, and cook until mostly browned, about 5 minutes. Drain if desired. Stir in garlic until fragrant, about 30 seconds.
Stir in crushed tomatoes, tomato sauce, tomato paste, sugar, basil, Italian seasoning, and fennel seeds. Simmer uncovered for 15 minutes, stirring occasionally. Season to taste with salt and pepper (I like 1 teaspoon salt and 1/2 teaspoon pepper). You should have about 2 quarts of sauce.
To make the cheese filling:
Meanwhile, in a large bowl, combine ricotta cheese with egg, parsley, and salt. Chill until the sauce is finished.
To assemble and bake the lasagna:
In the bottom of a 9-inch x 13-inch baking dish, spread 2 cups meat sauce. Arrange a single layer of uncooked noodles over the meat sauce (I sometimes do 3 full-size noodles lengthwise and then a partial noodle crosswise). Spread with a heaping 2/3 cup of the ricotta mixture. Top with about 1 1/2 cups (5 ounces) of mozzarella. Sprinkle with 1/3 cup Parmesan cheese.
Spoon 2 cups meat sauce over the cheese. Make another layer of noodles, ricotta mixture (heaping 2/3 cup), mozzarella (1 1/2 cups) and Parmesan (1/3 cup). Repeat layers 1 more time, for a total of 3 layers.
Spray a large piece of foil with nonstick spray and cover baking dish. Refrigerate at least 5 hours or overnight.
Preheat oven to 375 degrees. Bake, covered with foil, for 25 minutes. Remove foil and bake an until hot and bubbly, about 25 minutes longer. Cool 5 minutes, then garnish with parsley before serving if desired.
Ground meat: I prefer 1 pound each of ground beef and Italian sausage (2 pounds total). Or use just ground beef, just ground Italian sausage, or choose another ground meat entirely (such as ground turkey).
Sugar: Even a tablespoon is too much for some people. If you don't like the sound of sugar in your meat sauce, please leave it out. In my family, people add 1/4 cup or even up to 1/2 cup.
Fennel seeds: The seeds make the Italian sausage flavors pop. If you love the taste of a sweet tomato sauce, use just ground beef (no sausage), at least 1/4 cup sugar, and omit the fennel seeds.
Ricotta cheese: Make your own ricotta with just 4 ingredients: Milk, lemon juice, vinegar, and salt.
Lasagna noodles. NOT “oven ready” or “no-boil noodles." Those pre-cooked noodles will shred on your fork in the most unappetizing way, while the "real" noodles will soften in the fridge in just 5 hours
Yield: As written, the lasagna is made in a 9” by 13” baking dish, enough for 12 servings.
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Make ahead: Make this recipe up to 3 days before you need it and keep it in the refrigerator.
Freezer: Wrap the unbaked lasagna tightly in plastic wrap and freeze it for up to 2 months. Thaw overnight in the refrigerator, then bake as directed (preheat oven to 375 degrees, bake 25 minutes with foil, 25 minutes without foil). To bake the frozen lasagna straight from the freezer, bake 1 hour covered with foil and 24 minutes without the foil (the lasagna must reach 165 degrees on an internal thermometer).
Store-bought sauce: You’ll need 2 quarts of sauce for one pan of lasagna. You might want to add a little extra water if the sauce is on the thick side. This lasagna recipe uses a wet sauce so the noodles can soften in the liquid.
Disposable aluminum pans: I've made this in aluminum pans without a problem. They're just fine!
Pesto: Got a jar of pesto in the pantry, or homemade pesto in the refrigerator? Add a surprise layer somewhere for lots of extra flavor.