Start by large dicing the onion and thinly slicing and rinsing the leeks.
Peel and roughly chop the carrots.
In a 7–8-quart rondeau or Dutch oven pot, cook the onions in 2 tablespoons of unsalted butter over low to medium heat while occasionally stirring until well browned, which takes about 35 to 40 minutes.
In a separate large 7–8-quart rondeau or Dutch oven pot, roast the carrots in 2 tablespoons of unsalted butter over medium-high heat while frequently stirring until lightly caramelized, which takes about 20 to 25 minutes.
Deglaze the carrot pot with 1 cup of white wine and cook over medium-high heat until it is almost gone, or au sec. Turn the heat off and set it aside.
Once the onions are well caramelized, stir in the garlic, cook for 30 to 45 seconds or until fragrant, and then deglaze with 1 cup of white wine and cook over medium-high heat until it is almost gone, or au sec.
Transfer the carrots to the pot with the caramelized onions.
Next, add in the thyme sprigs and chicken stock and cook over low to medium heat for 20 to 25 minutes or until the carrots are very tender.
Remove the thyme sprigs and puree the carrot soup using a beurre mixer or in your blender until smooth. It’s ok if it’s a bit thick at this stage.
Next, blend in or whisk in the cream.
Adjust the seasonings with salt and ground white pepper.
Garnish with crème fraiche or thinned sour cream and optional minced fresh chives and thyme leaves.
Notes
Make-Ahead: For freshness, you can make this carrot soup up to 2 days ahead of time.How to Store: Cover the soup in the refrigerator for up to 5 days. Cover the soup and place in the freezer for up to 3 months. Thaw in the refrigerator for 1 day before reheating.How to Reheat: Place the desired amount into a medium-size pot and cook over low heat until hot.You could make this soup with yellow or purple carrots as well.If, for some reason, your soup does not thicken, add in a mixture of 3 tablespoons of cornstarch whisked with 6 tablespoons of cold water to make a slurry. Pour this mixture after the soup has been boiling for a few minutes and is not thickening.When using the blender, be sure to remove the center cap of the lid to let the heat escape. I usually hold a kitchen towel over the top so the soup doesn’t pop up once I turn on the blender.To thin the sour cream, mix 3 tablespoons of sour cream with 1 tablespoon of milk.If you want to keep this healthier, replace the amount of cream with stock.