Step 1

1.To prepare the ragu, place the tomatoes in a food processor and pulse until chunky. Set aside.

Step 2

2.In a large Dutch oven over medium-high heat, heat the olive oil. Add the carrots and onion and cook until the onion is translucent, 4 to 5 minutes. Add the garlic and cook for 1 minute, until fragrant. Add the ground beef, sausage, and pepperoni and season with the salt. Cook for about 10 minutes, or until the meat is browned all over, using a wooden spoon to break up the meat as it cooks. Add the tomato paste and cook for 4 to 5 minutes, until fragrant.

Step 3

3.Dust the flour over the mixture and stir well to combine. Stir in the reserved tomatoes, basil, marjoram, oregano, black pepper, and chili flakes. Bring to a boil, then cover and reduce the heat to a simmer. Cook for 45 minutes, stirring occasionally. Remove from the heat and set aside to cool. Using a large spoon, skim off any oil that accumulates on the surface. (The ragu can be prepared 2 to 3 days ahead of time; store it in a covered container in the refrigerator until ready to use.)

Step 4

4.To prepare the lasagna, in a large stockpot over medium-high heat, bring 2 gallons of water to a boil. Add 2 tablespoons of the salt. Add the lasagna noodles and stir gently to separate. Cook the lasagna noodles until al dente, 8 to 9 minutes. Meanwhile, prepare a large bowl of ice water. When the noodles are done, drain them, then plunge them immediately into the ice water for 30 seconds to stop the cooking process. Drain and spread the noodles on a rack.

Step 5

5.In a large bowl, combine the ricotta, half of the Parmesan, the egg, nutmeg, and pepper. Mix well to combine and set aside.

Step 6

6.In a large saute pan over medium-high heat, heat the olive oil. Add the garlic, spinach, and the remaining 1 teaspoon salt. Saute the spinach until tender and wilted, 1 to 2 minutes. Remove the pan from the heat and pour off any liquid. Transfer the spinach to a clean kitchen towel and twist it into a ball to squeeze out any excess moisture. Set aside.

Step 7

7.Preheat the oven to 350 degrees F. Have ready a heavy 10 x 14 x 3-inch lasagna pan.

Step 8

8.To assemble the lasagna, ladle 1 cup of the ragu into the bottom and around the sides of the pan. Arrange several lasagna noodles on top of the sauce, slightly overlapping them to create an even layer that completely covers the ragu. Spread 2 cups of the ragu over the lasagna noodles, followed by one-third of the ricotta mixture, one-quarter of the mozzarella, and one-third of the spinach.

Step 9

9.Arrange more noodles on top, overlapping to cover the spinach. Spread 2 cups ragu over the noodles, followed by half of the remaining ricotta, one-third of the mozzarella, and half of the spinach. Arrange more noodles on top. Spread 2 cups ragu over them, followed by the remaining ricotta, half of the remaining mozzarella, and the remaining spinach. Arrange more noodles on top. Spread the remaining ragu on top and sprinkle with the remaining mozzarella and Parmesan and the basil, marjoram and oregano.

Step 10

Cover the pan with heavy-grade plastic food wrap (or parchment paper), then wrap the whole pan tightly with aluminum foil. Place the pan on a baking sheet (to catch any drips) in the center of the oven. Bake for 1 hour. Remove the foil and plastic food wrap and bake for 20 minutes longer, until well browned around the edges and bubbling. Finish under the broiler if necessary. Cool for 20 minutes before serving.