1 (15-ounce) container whole milk ricotta cheese
1 (10-ounce) package frozen chopped spinach, thawed, squeezed dry
1 cup plus 2 tablespoons grated Parmesan
1 lb. ground round or sweet italian sausage (Or 1/2 lb. each)
2 large eggs, beaten to blend
3/4 teaspoon salt, plus more for salting water
1/2 teaspoon freshly ground black pepper
1 to 2 tablespoons olive oil
12 uncooked lasagna noodles
4 cups marinara sauce
1 cup shredded mozzarella (about 4 ounces)
Preheat the oven to 450 degrees F.
In a medium skillet over medium-high heat brown the meat.
Once cooked, remove from heat and let cool.
Whisk the ricotta, spinach, 1 cup Parmesan, cooled meat, eggs, salt, and pepper in a medium bowl to blend.
Add a tablespoon or 2 of oil to a large pot of boiling salted water.
Boil the noodles until just tender but still firm to bite. Drain.
Arrange the noodles in a single layer on a baking sheet to prevent them from sticking.
Butter a 13-by-9-by-2-inch glass baking dish.
Pour about 1.5 cups of marinara sauce on bottom of dish.
Lay out 4 lasagna noodles on a work surface, then spread about 3 tablespoons of ricotta mixture evenly over each noodle.
Starting at 1 end, roll each noodle like a jelly roll.
Lay the lasagna rolls seam side down, without touching, atop the marinara in the dish.
Repeat with the remaining noodles and ricotta mixture.
Spoon 1 cup of marinara sauce over the lasagna rolls.
Sprinkle the mozzarella and remaining 2 tablespoons of Parmesan over the lasagna rolls. Cover tightly with foil.
Bake until heated through and the sauce bubbles, about 20 minutes.
Uncover and bake until the cheese on top becomes golden, about 15 minutes longer.
Let stand for 10 minutes.
Meanwhile, heat the remaining marinara sauce in a heavy small saucepan over medium heat until hot, and serve alongside.