Step 1

Dice 1 medium yellow onion (about 1 1/2 cups) and finely chop 3 garlic cloves.

Step 2

Heat 1 tablespoon olive oil in a large frying pan or skillet over medium heat. Add the onion, garlic, 1 pound lean ground beef, 1 teaspoon Italian seasoning, 1 1/2 teaspoons kosher salt, and 1/4 teaspoon black pepper. Cook, breaking up the beef into small pieces with a wooden spoon, until the beef is cooked through and the onion is tender, 8 to 10 minutes.

Step 3

Add 1 (32-ounce) jar marinara sauce. Add 1/2 cup water to the now-empty marinara jar, seal the jar, and shake to loosen any remaining sauce from the jar. Pour into the pan, stir to combine, and bring to a simmer. Reduce the heat as needed to maintain a simmer and cook for 15 minutes to let the flavors meld. Meanwhile, heat the oven and prepare the remaining ingredients.

Step 4

Arrange a rack in the top third of the oven and heat the oven to 375ºF. Bring a large pot of heavily salted water to a boil over medium-high heat.

Step 5

Meanwhile, grate 8 ounces low-moisture mozzarella cheese on the large holes of a box grater (about 2 cups). Finely grate 2 ounces Parmesan cheese on the small holes of the box grater (about 3/4 cup), or measure out 1/2 cup store-bought grated. Pick the leaves from 12 fresh parsley sprigs and finely chop until you have 1/4 cup.

Step 6

Place half of the Parmesan, 3 tablespoons of the parsley, 1 (15-ounce) container ricotta cheese, 2 large eggs, and 1/2 teaspoon kosher salt in a medium bowl. Whisk with a fork until combined.

Step 7

Add 1 pound dried spaghetti to the boiling water and cook according to package directions for 1 minute less than al dente. Drain and return the pasta to the now-empty pot. Add half of the sauce (about 3 cups) and toss until combined.

Step 8

Transfer half of the pasta mixture into a 9x13-inch baking dish and arrange into an even layer. Dollop the ricotta mixture evenly over the pasta and spread into an even layer. Sprinkle with half of the mozzarella. Layer with the remaining pasta. Spread the remaining sauce over the pasta in an even layer, making sure the pasta is completely covered in sauce. Sprinkle with the remaining mozzarella and Parmesan.

Step 9

Bake uncovered until the edges are bubbling and the cheese is melted and browned in spots, about 30 minutes. Let cool for 10 minutes and garnish with the reserved parsley before cutting into pieces like a lasagna and serving.