Cook the Mushrooms: Heat a large non-stick stockpot over medium-high heat. Dry-sauté the chanterelles in batches until they release their liquid and turn golden brown. Alternatively, air fry the mushrooms for 10-13 minutes, being careful not to over-crisp.
Divide the Mushrooms: Remove about 1/2 cup cooked mushrooms for garnish, and about 1 cup of mushrooms for the creamy base.
Cook Aromatics: To the mushrooms remaining in the pot, add the onion. Use a small amount of water or broth to prevent sticking and sauté until the onions are soft and translucent. Add the minced garlic and dried marjoram and sauté for about a minute.
Simmer Potatoes: Add the Yukon Gold potatoes and 5 cups of liquid. Bring to a boil, then reduce the heat and simmer for 12–15 minutes until the potatoes are fork-tender.
Blend the Base: While the potatoes simmer, place one can of the rinsed white beans, cashews, powdered ginger, white miso paste, lemon juice, tamari, and optional nutritional yeast into a high-speed blender with 2 cups of liquid. Blend until completely silky.
Thicken and Adjust: Pour the blended mixture into the pot and stir in the second can of whole white beans. Simmer for 5 minutes. If the soup is too thick, stir in more liquid until you reach your desired thickness.
Finish: Stir in the baby spinach for 1 minute until wilted, then remove from heat.
Serve: Ladle into bowls and top with the reserved golden chanterelles.