Peel the carrots and parsnips, dice and set to the side. Cut the celery and onion.
Preheat a large dutch-oven on medium heat with the 1 tablespoon of grapeseed oil. Place the carrots, parsnips, celery and onions in the dutch oven. Mix well so that the oil is coated on the vegetables. Add 1 cup of vegetable stock, place lid on the pot and cook for 15 minutes. This will allow the vegetables to sweat.
While the vegetables are sweating begin to peel the butternut squash. Add the butternut squash to the soup pot followed by the salt, black pepper, and Italian seasoning. Mix well and then add in the remaining vegetable broth and the red lentils. Place the lid on the pot and cook for 20 minutes. Mix periodically. Turn the burner off and add in the diced mushrooms, tomato, and spinach. Place the lid on the pot, and let stand for 5 minutes.
Divide soup evenly among bowls and top with a tablespoon of yogurt.