spinach lasagna recipe

ngredients: 10 lasagna noodles 1 tablespoon olive oil 1 medium onion, diced 3 cloves garlic, minced 2 (10-ounce) packages frozen chopped spinach, thawed and drained 4 cups ricotta cheese 2 large eggs 1/2 cup grated Parmesan cheese 2 cups shredded mozzarella cheese 4 cups marinara sauce (store-bought or homemade)