1 tablespoon olive oil
4 cups sliced leeks (tender parts only from about 3, trimmed)
1 large garlic clove, minced
1 qt. reduced-sodium chicken or vegetable broth
3 large russet potatoes, peeled and chopped
1 cup half-and-half
2 teaspoons kosher salt
1. Heat oil in a medium pot over medium heat. Cook leeks, stirring often until softened, about 5 minutes. Measure out 1/4 cup leeks and set aside. Add garlic to remaining leeks in pot and cook until fragrant, about 2 minutes. Increase heat to high. Add broth and potatoes and cook, covered, until potatoes are tender, 10 to 15 minutes. Add half-and-half and salt.
2. Working in batches, whirl soup in a blender to purée. Divide soup among 4 bowls and top each with about 1 tbsp. reserved leeks.