Turn stove to high. Add the olive oil to your large soup pot.
Add in the onion, garlic, bay leaf and celery. Cook on high for 2-3 minutes, stirring ingredients every minute. You want the onion to caramelize a bit and the onion to toast to also caramelize the flavor a bit.
Add in the veggie broth, water, potato, carrots, parsley, nutritional yeast, vegan sausage and pasta. Bring to a boil. Cover pot with lid and reduce heat to medium-low. Cook, covered for about 15 minutes.
Simmer the soup on medium, lid off, for another five minutes to thicken the consistency. The pasta should be cooked by now, all the veggies tender. At this point you are just developing the flavors a bit more.
Add in the spinach or kale and optional black pepper. Stir the greens into the soup. Cover the lid one more time and bring soup up to high - just a minute or so. The heat will quickly soften the greens.
Uncover lid and turn off heat. Serve warm. If desired: you can leave the soup on low, simmering for another ten minutes, covered to develop the flavors and soften the ingredients even more. This soup is delicious same day, as well as served as leftovers the next day.