01 -
Preheat the 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. Add lasagna noodles and cook until al dente. Drain and set aside.
03 -
Heat olive oil in a large skillet over medium heat. Add chopped onion and cook until translucent, about 3 to 4 minutes. Add minced garlic and cook for 1 minute more.
04 -
Add sliced mushrooms, dried thyme, salt, and pepper to the skillet. Cook until mushrooms are tender and moisture has evaporated.
05 -
Add chopped spinach leaves to the skillet and cook until wilted, approximately 2 to 3 minutes. Remove from heat.
06 -
Spread a thin layer of marinara sauce on the bottom of the baking dish. Arrange three lasagna noodles over the sauce. Spread half of the ricotta cheese over noodles, then evenly top with half the mushroom and spinach mixture. Sprinkle one-third of mozzarella and Parmesan cheeses. Repeat the layers with remaining noodles, ricotta, mushrooms, and cheeses. Finish with remaining marinara sauce on top.
07 -
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes.
08 -
Remove foil and continue baking for 10 to 15 minutes until cheese is bubbly and golden brown.