Melt the butter in a soup pot over medium high heat, and add the potatoes with a big pinch of sea salt. Cook until the potatoes start to slightly brown and crisp. This will take a good 5-10 minutes depending on how big you cubed your potatoes.
Add the spring onion and garlic, stir, and cook over medium heat for a few minutes until fragrant and the spring onion wilts and the whites soften.
Pour in the wine, scrape up any bits at the bottom of the soup pot, and lightly simmer for one minute.
Add the bone broth and spinach and simmer for 5 minutes.
Turn off the heat, blend the soup with your immersion blender or regular blender, and then sea salt and pepper the soup to your taste.
Top the soup with your choice of cheese or a dollop of sour cream.