3 medium russet potatoes (about 2 1/4 lb.), peeled and chopped
3 leeks, white and light green parts only, thinly sliced
3 celery stalks, chopped, plus yellow leaves for garnish (optional)
3 garlic cloves, finely chopped
¼ cup chopped shallots
6 c. chicken broth
6 sprigs fresh thyme
1 1/2 tsp. kosher salt, plus more to taste
3/4 tsp. ground black pepper, plus more to taste
1 c. heavy cream
2 oz cream cheese
Hot sauce and fried onions, optional
In a medium Dutch oven, heat the oil and butter over medium heat. Add shallots and sauté for 2-3 minutes. Add the potatoes, leeks and celery. Cook, stirring, until the leeks are tender, 6 to 8 minutes. Add the garlic and cook, stirring, until fragrant, about 30 seconds.
Stir in the chicken broth, thyme sprigs, salt and pepper. Bring to a simmer over medium-high heat. Reduce the heat to medium-low and cook, uncovered, until the potatoes are tender, 15 to 20 minutes.
Remove the thyme sprigs. Transfer about 4 cups of the soup to a blender. Remove the top insert from the lid and cover with a kitchen towel. Puree until smooth, 30 seconds. Add to Dutch oven with the remaining chunky soup. Stir in the cream and cream cheese and cook over medium-low heat, stirring, until the soup is slightly thickened, 10 to 15 minutes.
Season the soup with more salt and pepper. Garnish with thyme leaves, and fried onions.