In a large pot or Dutch oven, heat butter over medium until melted. Add shallots and a generous sprinkle of salt. Cook for 5 minutes, stirring occasionally until browned.
Add sweet potato and cook 10 minutes, stiring occasionally, then add thyme, broth, orange juice and zest.
Bring to a boil, then reduce heat to a simmer and cover for 25 minutes or until the sweet potatoes are fork tender. Allow to cool slightly.
Using an immersion in the pot or high speed blender in batches, process until smooth. Add sugar, nutmeg, salt and pepper. Season to taste; serve immediately or return to the pot and simmer until ready to enjoy.
Garnish ideas: pecans, pumpkin seeds and nutmeg.
Notes
If the soup is too thick, thin with a little vegetable broth.
This soup keeps best in the refrigerator up to 3-4 days and freezes for a few months.