Wash hands with soap and water.
Scrub sweet potatoes with a clean vegetable brush under running water. Once clean, peel and cube the potatoes.
In a large pot, boil potatoes until they can be pierced with a fork. Remove from heat and drain the excess water.
Melt the butter over low to medium heat in a large pot. Add flour and stir constantly until the roux achieves a light caramel color.
Add the chicken broth and brown sugar to the pot. Bring to a boil, then lower to a simmer
Stir in the cooked sweet potatoes, ginger, cinnamon and nutmeg. Bring to a simmer again and cook for 5 minutes.
Remove pot from the heat and using a blender, puree the soup in small batches. After all the soup has been pureed return to the pot.
Add milk, salt and pepper.
Reheat the soup to steaming and enjoy!
If you so desire, garnish with chopped chives or green onion (gently rub chives and onion under cold running water), Greek yogurt or sour cream, toasted pecans or walnuts.
When reheating leftover soup, reheat it until internal temperature reaches 165°F on a food thermometer.