Step 1

Heat the oven to 400ºF. Arrange a rack in the middle of the oven and heat the oven to 400°F.

Step 2

Brown the beef and onion. Finely chop 1 medium yellow onion. Heat 1 tablespoon olive oil in a 12-inch or larger regular or cast iron skillet over medium-high heat until shimmering. Add the onion, 1 pound lean ground beef, 1/2 teaspoon kosher salt, and 1/4 teaspoon freshly ground black pepper, and cook, breaking the beef up into small pieces with a wooden spoon, until the beef is cooked through, 6 to 8 minutes. Remove from the heat and let cool for 5 minutes.

Step 3

Prepare the baking dish and assemble the meat sauce. Open 1 (24 to 25-ounce) jar marinara sauce (3 cups). Spread a thin layer of the sauce in the bottom of a 9x13-inch baking dish. Stir the remaining sauce into the ground beef mixture.

Step 4

Begin layering the lasagna. Shred 12 ounces low-moisture mozzarella cheese if needed (3 cups). Place 5 lasagna noodles in the baking dish, breaking them if needed to create a single layer (it’s OK if the noodles overlap slightly). Dollop and spread 1 cup of the ricotta cheese over the noodles. Dollop and spread about 1 1/2 cups of the meat sauce on the ricotta, then sprinkle with 1 cup of the mozzarella.

Step 5

Continue layering the lasagna. Arrange 5 more noodles over the mozzarella, followed by 1 cup of the ricotta cheese, 1 1/2 cups of the meat sauce, and 1 cup of the mozzarella. Top with a final layer of 5 noodles and the remaining sauce, spreading the sauce thin so that it almost completely covers the noodles. (Reserve the remaining 1 cup mozzarella for the end of baking.) Cover the dish tightly with aluminum foil.

Step 6

Bake the lasagna for 1 hour. Bake for 1 hour. Check to make sure the noodles are done by poking the lasagna with a knife; the knife should slide easily through all the layers. If it doesn't, cover and cook for 15 minutes more.

Step 7

Sprinkle with the remaining mozzarella and finish baking. Uncover the lasagna and sprinkle with the remaining 1 cup mozzarella. Bake uncovered until the mozzarella is melted and lightly browned, and the sauce is bubbling, 8 to 10 minutes more.

Step 8

Cool the lasagna for 15 minutes. Let the lasagna cool on a wire rack for at least 15 minutes before serving.