In a large pot, melt the butter over medium heat until bubbly. Add the chopped onion and minced garlic, sautéing for about 5 minutes until the onion is translucent.

Introduce the diced potatoes and vegetable broth. Bring to a gentle boil, then reduce to a simmer. Cook uncovered for 15-20 minutes until potatoes are tender.

Stir in the fresh spinach until wilted, about 2-3 minutes.

Transfer the soup in batches to a high-speed blender and blend until silky and smooth.

Return the blended soup to the pot. Reduce heat to low and whisk in the heavy cream or coconut milk along with a tablespoon of butter. Season with salt, pepper, and nutmeg to taste, heating through for about 5 minutes.

Ladle soup into bowls, garnishing with Parmesan cheese and fresh herbs. Serve alongside crusty artisan bread.