First, preheat oven to 375ºF and spray a baking dish or cake pan with nonstick cooking spray.
Prep 12 lasagna noodles by following the directions on the box. Set aside.
Prep sweet potato cheese by mixing together whole milk ricotta, cottage cheese, sweet potato puree, and rosemary. Set aside.
Prep sauce by heating olive oil in a skillet. Then, add in onion and sauté for about 5 minutes or until almost translucent. Add spinach and sauté for an additional 2ish minutes until it has cooked down. Add marinara sauce and spice and let simmer for 2-3 more minutes on low.
Prepare lasagna dish by layering noodles, cheese, and sauce. You should end with a layer of noodles on the top.
Bake at 375ºF for 25 minutes Then, sprinkle on mozzarella cheese and bake for an additional 5-10 minutes.