1. Preheat the oven to 375F. Bring a large pot of water and 2 teaspoons salt to a boil for the noodles. Heat 1 teaspoon of olive oil in a large sauté pan over medium heat. Add the sausage and cook, stirring often, until it's no longer pink, about 6-8 minutes. Remove the sausage to a medium bowl with a slotted spoon.

2. Add a splash of water to the now empty pan to release the browned bits, scraping with a wooden spoon. When scraped mostly clean and the water mostly evaporated, add the minced garlic and a little oil to brown slightly. Add the spinach leaves and cook, adding another splash of water to help it wilt. Once all the water is evaporated and the spinach is thoroughly wilted, add it to the bowl with the sausage and mix them together.

3. When the pasta water boils, add the lasagna noodles and stir. Stir gently and often to prevent them from sticking together. Just before the pasta is cooked al dente, drain it in a colander. Toss with a little olive oil, and lay the strips out flat on pieces of waxed paper or a kitchen towel. Cover with a damp kitchen towel to keep them moist.

4. Rub the baking dish with a little olive oil. Mix together 1/2 the parmesan, the ricotta and the mozzarella in a medium bowl. Pour about 1/4 of the sauce into the bottom of the baking dish. Then add a single layer of noodles, lengthwise -- five should cover the width. The lasagna can overlap some. With a wide spatula, spread on about 1/3 of the cheese mixture. Top with a layer of the sausage and spinach. Repeat the process (sauce, pasta, cheese, meat and spinach) twice more, ending with a final layer of noodles and a coating of sauce. Sprinkle the top with the remaining parmesan.

5. Cover the dish with foil, and bake it in the oven for about 45 minutes. Remove the foil and bake about 20 more minutes until top is crusty around the edges and golden brown. Let the lasagna to rest 20 minutes before serving.