Spread a little tomato sauce on the bottom of a 9 x 13-inch baking pan. Those aluminum ones you buy at the supermarket work great too.
Cover with a layer of noodles making sure to overlap the edges a little. Add a little more sauce and add some of the cheese mix, spinach, roasted peppers, and mozzarella.
Add another layer of noodles and repeat the process by adding sauce, cheese mix, spinach, peppers, and mozzarella.
Finish off by adding more noodles, sauce, remaining Parmesan cheese, and the rest of the mozzarella.
Bake uncovered in the preheated oven for 25 minutes.
Add a layer of aluminum foil and bake another 10 minutes.
Remove lasagna from oven and let stand for 10 minutes before serving.