Melt two tablespoons salted Finlandia butter in a large pot over medium heat. Add the onion and stir for about 2 minutes. Add garlic, sage, salt, and pepper, then cook, stirring frequently, until golden, about 5 minutes.
Add stock, pumpkin puree, cinnamon, and maple syrup, then cover and simmer for 20 minutes. Use an immersion blender to puree until silky smooth.
Add the remaining 4 tablespoons of salted Finlandia butter to a small pot over medium heat. Swirl it around until it starts to turn golden and smell nutty, about 4 minutes. Remove it from the heat as soon as it begins to turn brown.
Stir browned butter into the soup along with freshly grated nutmeg. Taste and adjust seasoning as needed.
Ladle soup into bowls, then top with freshly cracked black pepper, toasted pumpkin seeds, and a drizzle of olive oil. Serve hot.