Separate florets from stalks. Peel and slice stalks and reserve. In a medium soup pot, heat coconut oil over medium-low heat, and add onion, shallot and garlic. Cook and stir until golden, about 6-10 minutes. Add reserved sliced broccoli stalks, diced potato, thyme, salt, pepper and cayenne and toss to mix. Stir in vegetable broth and cover and simmer soup about ten minutes. Add broccoli florets and simmer about ten minutes more, or until diced potato and broccoli are tender. Stir in nutritional yeast. Puree with immersion blender, blender or food processor and serve. Garnish with paprika and/or grated cheddar cheese if desired.