As the days shorten into autumn, leeks , in their mounded soil, continue to grow and mature making them a perfect companion with potatoes. They can also be left in the ground, well into winter, as long as they are protected to prevent the ground from freezing solid.
This soup is great to start off a chilly autumn dinner or to serve as the main course on a Sunday evening with some crusty bread and a salad. This time around I decided to leave it more rustic by not pureéing it until it was absolutely smooth.
Also, since garlic chives are part of the allium family, I decided to garnish it with some garlic chive flowers. One could also garnish the soup with some fresh thyme leaves or even a dollop of crème fraîche.
This recipe can easily be cut in half, but why do that since it freezes so beautifully.
Makes about 12 cups
2 large leeks, white and pale green part only
1 tablespoon unsalted butter
1 teaspoon kosher salt, or to taste
½ teaspoon freshly ground white pepper, or to taste
3 cloves of garlic, minced
2 teaspoons fresh chopped thyme
4 cups chicken or vegetable stock, preferably homemade
2 – 3 cups whole milk, preferably organic, I used Cedar Summit Farm 
1 1/2 pounds boiling potatoes, such as Yukon Gold or Yellow Finn, peeled and cut into 1/2 –inch dice
In a large bowl filled with cold water add leeks that have been split lengthwise and cut into ¼ inch slices. Wash thoroughly, allowing any sand to fall to the bottom of the bowl. Gently lift out the sliced leeks and drain in a colander.
In a large heavy saucepan cook the leeks in the butter with salt and pepper to taste, covered, over moderately low heat. Stir occasionally, for 8 to 10 minutes, or until they are softened but not browned. Add the garlic and thyme and sauté for about 30 seconds.
Add the stock and potatoes. Simmer the mixture, covered, for 20 minutes, or until the potatoes are tender when pierced with the tip of a paring knife.
In a blender purée the soup adding a little milk as necessary to keep the blender going. Return soup to the saucepan to reheat, being careful not to let the soup boil. Season with salt and pepper if desired and serve in warm soup bowls.