Gather all ingredients. Preheat the oven to 350 degrees F (175 degrees C).
2
Bring a large pot of lightly salted water to a boil. Add lasagna noodles and cook for 8 to 10 minutes or until al dente; drain.
3
Meanwhile, heat olive oil in a skillet over medium-high heat. Add mushrooms, onions, and garlic and cook until onions are tender; drain excess liquid and cool.
