In a skillet on medium heat, sauté onions and garlic in olive oil, add spinach till wilted, and set aside after all water cooks off.
Bring a large pot of water to the boil and boil the lasagna sheets for 5 minutes each.
Preheat the oven to 350F. In a bowl mix the spinach and onion along with the ricotta, egg, nutmeg, fresh basil, thyme, ¼ cup Parmesan, 1 cup mozzarella, and a pinch of salt and pepper. Mix until it forms a paste.
Divide this between lasagna sheets and roll them up.
Spoon a layer of marinara sauce onto the bottom of a 9 x 13 inch casserole dish and arrange the rolls into the dish in lines.
Add the rest of the marinara sauce on top. Sprinkle over the rest of the mozzarella and Parmesan. Place it into the oven to bake for 30 minutes until the cheese is bubbling.