01 -
Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish with cooking spray or olive oil.
02 -
Bring a large pot of salted water to a boil. Cook lasagna noodles according to package instructions until al dente. Drain and set aside.
03 -
Heat olive oil in a large skillet over medium heat. Add onion and cook until translucent, about 3-4 minutes. Add garlic and cook for an additional minute until fragrant.
04 -
Add mushrooms, dried thyme, salt, and pepper to the skillet. Cook until mushrooms are tender and liquid has evaporated.
05 -
Add chopped spinach to the mushroom mixture and cook until wilted, about 2-3 minutes. Remove from heat and set aside.
06 -
Spread a thin layer of marinara sauce on the bottom of the prepared baking dish. Arrange three lasagna noodles on top of the sauce.
07 -
Spread half of the ricotta cheese over the noodles, followed by half of the mushroom-spinach mixture. Sprinkle a third of the mozzarella and Parmesan cheeses over the top.
08 -
Repeat with another layer of three noodles, remaining ricotta, remaining mushroom-spinach mixture, and another third of the mozzarella and Parmesan.
09 -
Place the final three noodles on top, cover with remaining marinara sauce, and sprinkle with remaining cheese.
10 -
Cover baking dish with aluminum foil and bake for 25 minutes. Remove foil and continue baking for 10-15 minutes until cheese is bubbly and golden brown.
11 -
Let lasagna rest for 10 minutes before serving. Garnish with fresh basil leaves.