- 4 tablespoons unsalted butter
- 1 1/2 pounds trimmed leeks, cleaned and thinly cut
- 2 teaspoons kosher salt, plus more to taste
- 1 1/4 pounds Yukon Gold potatoes, peeled, cut into eighths
- 3 cups chicken or vegetable broth, or more as needed to adjust thickness
- 1 cup heavy cream
- 1/2 cup creme fraiche
- 1 pinch cayenne pepper
- Chopped fresh chives for garnish
- Melt butter in soup pot over medium-high heat. Add leeks and salt; cook until leeks begin to wilt. Reduce heat to medium or medium-low and cook until soft and almost pastelike, 30 to 40 minutes.
- Place potatoes in the pot; add chicken broth. Adjust heat so mixture simmers slowly. Cook until potatoes are soft, about 30 minutes. Puree mixture with an immersion blender or in batches in a blender. Whisk in heavy cream and creme fraiche. Heat over medium heat. Add more salt, if needed, and cayenne pepper. Do not boil.
- Serve with a drizzle of creme fraiche and a sprinkle of chopped chives.