Step 1

Preheat oven to 350 degrees F. Coat a 9 by 13-inch baking dish with cooking spray.

Step 2

Bring a large pot of lightly salted water to a boil. Cook lasagna, stirring occasionally until soft and pliable but not yet al dente, about 5 minutes. Drain and rinse with cold water.

Step 3

Meanwhile, coat a large non-stick skillet with cooking spray. Add beef, mushrooms and Italian Seasoning and set over medium-high heat. Cook, breaking up beef with a wooden spoon until no-longer pink and the liquid is evaporated, 7 to 8 minutes. Add garlic and cook, stirring 30 seconds. Add tomatoes and salt and stir to combine. Bring to a simmer, while adding baby spinach by handfuls, stirring to wilt until the whole amount is completely wilted into the beef mixture, 3 to 4 minutes. Remove from the heat and stir in basil.

Step 4

Beat egg in a medium bowl. Add ricotta and pepper and stir until completely combined.

Step 5

Spread ½ cup tomato mixture in the bottom of the prepared baking dish. (Tip: Remove any large chunks of beef and add them back to the skillet of sauce.) Layer three lasagna noodles vertically into the baking dish; cut one more noodle as necessary and place horizontally to fill in the space at the end of the other three. Top with 1 ½ cups tomato mixture. Dot with half of the ricotta mixture. Sprinkle with ¾ cup mozzarella. Top with 3 ½ more noodles, 1 ½ cups tomato mixture. Dot with the remaining half of the ricotta mixture and top with ¾ cup mozzarella. Top with the remaining noodles. Spread the remaining tomato mixture (about 1 cup) evenly over the top. Cover with aluminum foil.

Step 6

Bake until the lasagna is steaming hot all the way through, 40 to 50 minutes. Remove foil, sprinkle with the remaining ½ cup mozzarella and Parmesan. Bake until the mozzarella on top is just melted but not browned, about 10 minutes.

Step 7

Let lasagna cool 10 to 15 minutes before sprinkling with additional basil and slicing it into 12 servings.