6 sheets no-boil lasagna noodles, or 6 regular noodles, cooked
1/4 cup Parmesan cheese, grated
4 cups fresh baby spinach
2 cups mushrooms, sliced
Salt and pepper, to taste
Stove with simmer control
Large deep skillet or 2 quart pot
In a skillet, heat 2 tablespoons of the olive oil over medium-high heat. Add sliced mushrooms and saute for 5 mins. Remove from the skillet and set aside.
Add the garlic and onions and cook until onions are translucent, stirring frequently. Add the crushed red chili flakes and cook for a few seconds. Add ground beef, if using, and cook for about 5 minutes or until meat is browned and cooked through. Add crushed tomatoes and set can aside. Season with salt and pepper to taste.
Pour about 2/3 of the sauce back into the can, and leave 1/3 in the bottom of the pan.
Start by layering noodles over the sauce and then layer ricotta, mushrooms, spinach, mozzarella and drizzle with olive oil. Repeat layering starting with more sauce until all ingredients are used, ending with mozzarella. Top with the Parmesan cheese.
Cover and simmer until the lasagna noodles are cooked and the cheese melts. Remove from the heat and let the lasagna cool for a few minutes before serving.