Set your oven to 350 degrees. Peel and chop the vegetables into similar sizes, and toss in a little olive oil. Roast for 35 minutes, tossing occasionally to assure that they do not burn or stick to the bottom of the pan. Total cooking time will be about 1 hour, but check after about 35-45 minutes to see if any are softening quicker than others (and pop them in the soup pot so they all cook evenly.)
Heat the vegetable stock in a large pot. Add dried herbs and garlic.
Splash the roasting pan with some of the vegetable stock, and scrape it all into the pot for some caramelized flavor.
Optional roux add-in: Add 2 tbsp of butter and 2 tbsp flour to the veggie roasting pan set over medium high heat on the stove top (only if you used a stovetop and oven-safe pan. Otherwise, just make in a separate pot.) Whisk the flour and butter together until it foams. Lower the heat and cook for 2-3 minutes. Add 1 cup of liquid from the stock pot or part stock-part milk or half and half for a creamier stew. Raise the heat to medium high. Thicken while whisking for about 7-8 minutes, and then add it to the soup pot.
Right before you serve, remove the soup from heat and stir in the spinach and parsley.