Potato and Leek Soup

3 tablespoons butter
2 leeks (white and pale green parts only), halved lengthwise, thinly sliced
3-4 potatoes (about 18 ounces total), peeled, diced
2-3 cloves garlic, minced
4 1/2 cups vegetable or chicken stock
1 bay leaf
1/ tsp dried thyme
2 tablespoons chopped fresh chives
Heat the butter with a splash of extra-virgin olive oil in a heavy pot. Saute the leeks and garlic until the leeks are tender. Add potatoes and cook until they begin to soften, but before they start to brown. Add the stock, bay leaf and thyme, and simmer until potatoes are very tender, about 30 minutes. Use an immersion blender or food processor to blend soup until it is smooth and creamy. Garnish with chives, if available.