Spray the slow cooker with nonstick cooking spray.
Layer the diced eggplant in the bottom of the pot. Season with 1 tablespoon of salt and several grinds of pepper. Sprinkle eggplant with garlic and parsley. Drizzle with 3 tablespoons of olive oil. Sprinkle with 3 tablespoons of Parmesan.
Layer zucchini on top of eggplant. Sprinkle with more salt, pepper and 1-2 tablespoons of Parmesan cheese.
Layer onions on top of zucchini; sprinkle with salt and pepper.
Layer mushrooms on top of onions; drizzle with 1 tablespoon of olive oil.
Layer tomato slices on the top; sprinkle with salt, pepper and 3 tablespoons of Parmesan cheese.
Put the lid on the slow cooker and cook on low for 6-8 hours.
Serve in a flat bowl over noodles. Ladle some of the broth on top and sprinkle with a little more Parmesan cheese and fresh parsley for garnish.