Pulse chop (about 5 pulses) the cremini mushrooms in batches in food processor fitted with blade, until they resemble cooked crumbled ground beef.

Heat olive oil in Dutch oven over medium-high heat. Add mushrooms; cook stirring constantly until most of the moisture is evaporated, about 5 minutes. Add marinara sauce; stir to combine. Set aside.

Squeeze liquid from spinach, first in handfuls, and then in paper towels. Set aside.

Combine ricotta cheese and egg; mix well. Set aside.

Assemble lasagnas as follows. (Note: Assembly is based on 8 x 6-inch baking dish. If using 13 x 9-inch baking dish, double ingredients.)

First Layer: Spread ⅔ cup of the mushroom sauce in the bottom of a 8 x 6-inch baking dish. Arrange two noodles cut to size lengthwise over the mushroom sauce. Top with ⅓ cup of spinach, 2 ½-ounces of the shredded mozzarella cheese, and ⅔-ounce of the grated Parmesan cheese.

Second Layer: Spread ⅔ cup of the mushroom sauce over the first layer. Arrange two noodles cut to size lengthwise over the mushroom sauce. Top with ½ cup of the ricotta cheese mixed with egg, ⅓ cup of spinach, 2 ⅔-ounces of the shredded mozzarella, and ⅔-ounce of the grated Parmesan cheese.

Third Layer: Spread ⅔ cup of the mushroom sauce over the second layer. Arrange two noodles cut to size lengthwise over the mushroom sauce. Top with ½ cup of the ricotta cheese mixed with egg, ⅓ cup of spinach, 2 ⅔-ounces of the shredded mozzarella, and ⅔-ounce of the grated Parmesan cheese.

Preheat oven to 375° F.

Cover lasagna with aluminum foil. Bake covered in preheated oven for 20 minutes. Remove aluminum foil. Bake uncovered 15 minutes, or until golden brown and bubbly. Remove from oven; let rest 10 minutes before serving.

Yield: 4 servings per 8 x 6-inch pan; 2 lasagnas total.