1. Place a large (12- to 13-inch) ovenproof cast iron skillet with a lid or a 10-inch Dutch oven on the stovetop over medium heat. Once hot, add the olive oil and onion and cook for 5 minutes, or until the onion is translucent, stirring frequently. Add the garlic and sliced mushrooms. Cook, stirring frequently, for about 4 minutes. Add the pasta sauce, tomato sauce, 1 cup of water, and the seasonings. Stir to combine and bring to a simmer.

2. Add the grated carrot, zucchini, and spinach and stir to combine. Add the ricotta cheese, stirring to incorporate as evenly as possible.

3. Break the lasagna sheets into large pieces (3-4 pieces per sheet) and add them to the pan. Make sure they are evenly spread, pressing them into the sauce to ensure all edges are covered in liquid. Add the additional cup of water. Cover and let simmer for approximately 10 minutes, or until lasagna sheets are cooked al dente. Stir once or twice in between.

4. While the lasagna cooks on the stovetop, preheat the oven to 375° F.

5. Once the lasagna sheets are al dente remove the lid, top with mozzarella and place in the oven for approximately 10 minutes, or until the cheese is melted and beginning to brown.

6. Remove from the oven and use a large spoon to scoop and serve with optional toppings.