Lasagna Casserole

Preheat the oven to 375 degrees F (190 degrees C). Position a rack in the center of the oven, approximately 10 inches from the heat source. (5 minutes)

Bring a large pot of salted water to a rolling boil. Add the pasta shells and cook, stirring occasionally, until they are almost tender, about 7 minutes. Drain the pasta in a colander, then return it to the pot and toss with 1 tablespoon of olive oil. (10 minutes)

In a large Dutch oven, heat the remaining 3 tablespoons of olive oil over medium-high heat. Add the ground sirloin and sausage, allowing it to cook undisturbed until the bottom side is lightly browned, approximately 6 minutes. Stir, and continue cooking, breaking the meat into smaller pieces with a wooden spoon, until it is fully cooked through, about 4 minutes. (10 minutes)

Reduce the heat to medium. Add the finely chopped onion and thinly sliced garlic, cooking and stirring frequently until softened, around 4 minutes. (5 minutes)

Stir in the marinara sauce, fresh basil, and crushed red pepper. Remove the ragu from the heat. (2 minutes)

In a bowl, combine the ricotta cheese, Parmigiano-Reggiano, heavy cream, and kosher salt. Mix well. (3 minutes)

To assemble the casserole, spread about 2 cups of the ragu evenly in the bottom of a 13- x 9-inch baking dish. Spoon half of the cooked pasta shells over the sauce. Dollop half of the ricotta mixture over the pasta, then sprinkle with 1 cup of mozzarella cheese. Spoon the remaining pasta over the mozzarella cheese. Spread the remaining ragu evenly over the pasta mixture, and dollop with the remaining ricotta mixture. Top with the remaining 1/2 cup of mozzarella cheese. Cover the lasagna with a large sheet of aluminum foil that has been lightly sprayed with cooking spray to prevent the cheese from sticking. (15 minutes)

Bake in the preheated oven for 30 minutes. Remove from the oven and carefully remove the foil. Increase the oven temperature to broil, keeping the rack about 10 inches from the heat source; preheat for 5 minutes. Return the baking dish to the oven. Broil until the cheese is beautifully browned in spots, approximately 5 to 8 minutes. (43 minutes)