Prepare the cashew cream. Add all the "cashew cream" ingredients into a high-speed blender and blend on high until smooth. Leave half of the cashews cream in the blender and set the other half aside for serving.
Sauté the aromatics. Heat the olive oil in a medium pot over medium heat. Add the onions and garlic and sauté until translucent, 5-7 minutes.
Cook the broccoli. Add the broccoli and broth into the pot with the aromatics and bring to a boil over high heat. Reduce the heat to medium-low, season with salt (if the broth doesn’t contain salt already), and simmer, partially covered, until the broccoli begins to soften but is still firm and bright green, about 2 minutes.
Blend the broccoli. Transfer the broccoli with the aromatics and vegetable broth into the blender with the cashew cream. Add the parsley, nutritional yeast, lemon juice, and salt and blend on high until completely smooth. If using a Vitamix blender, blend until heavy steam escapes from the vented lid, 5-6 minutes.
Season. Taste and adjust the flavor as needed, adding more salt for saltiness, nutritional yeast for cheesiness, and lemon juice for acidity.
Serve. Pour the soup into serving bowls - it will be hot straight out of the blender (if using Vitamix). Garnish with a few swirls of the set aside cashew cream and a few fresh parsley leaves.
Store. Leftover soup keeps well, covered, in the refrigerator for 3-4 days. For longer term storage, freeze in an airtight container for up to 3 months.
Reheat. Transfer frozen soup into the refrigerator 24 hours before reheating to thaw slightly. Reheat in a pot on the stovetop over medium-low heat, stirring frequently, until hot. Add ¼ cup/60 ml water/broth at a time if too thick.