Heat 1 Tablespoon of oil in a large, shallow pan over medium high heat. When the oil is hot but not smoking, add the sausage. Cook, breaking the sausage up with a spoon, until the sausage is browned and cooked though – 5-8 minutes. Using a slotted spoon, transfer the sausage to a plate.
Add the garlic and red pepper flakes to the pan and cook 1-2 minutes, or until fragrant. Stir in the zucchini and eggplant. Cook 2-3 minutes, or until browned. Add the pasta and water. Bring to a boil, then reduce heat to medium and simmer 11-12 minutes, or until pasta is cooked al dente and most of the water is evaporated.
Add the sausage, spinach, and parmesan. Stir until the spinach is wilted. Season to taste with salt and pepper. If desired, drizzle with 2-3 Tablespoons of olive oil.