Easy Lasagna

1 tablespoon olive oil
1 pound 80/20 ground beef
Kosher salt and freshly ground black pepper
One 24-ounce jar marinara sauce
2 tablespoons balsamic vinegar
1 tablespoon unsalted butter
One 16-ounce tub whole-milk ricotta (about 2 cups)
1 cup grated Parmesan (about 4 ounces)
1 large egg, beaten
2 cups shredded mozzarella (about 8 ounces)
12 no-boil lasagna noodles

Directions

1. Preheat the oven to 425 degrees F.
2. Heat the olive oil in a large skillet over medium-high heat. Add the ground beef, 2 teaspoons salt and a few grinds of pepper and cook, breaking it up with a wooden spoon and stirring occasionally, until the beef is browned and no longer pink in the middle, 5 to 6 minutes. Pour in the marinara sauce and bring to a simmer. Lower the heat to medium and continue to simmer until slightly reduced, 5 to 6 minutes. Add the balsamic vinegar and butter and stir until the butter is melted.
3. Meanwhile, combine the ricotta, Parmesan, egg, 1 cup of the mozzarella, 1 teaspoon salt and a few grinds of pepper in a medium bowl.
4. Spoon 1/2 cup of the sauce onto the bottom of a 9-by-13-inch baking dish. Lay 3 of the lasagna noodles over the sauce. Spread a third of the cheese mixture over the noodles, then spread a third of the remaining sauce over top. Repeat 2 more times, then lay the last 3 noodles on top. Sprinkle with the remaining 1 cup mozzarella.
5. Bake until the noodles are softened, the cheese on top is melted and turning brown in some spots and the sauce is bubbling around the edges, about 30 minutes. Let cool for 5 minutes before slicing and serving.