Cream of Broccoli Soup

Melt butter in a large saucepan over medium-high heat. Add leeks and celery; cook, stirring occasionally, until softened, 6 to 8 minutes. Add garlic; cook, stirring constantly, until fragrant, about 1 minute.

Add broccoli and broth; bring to a boil. Reduce heat to medium; cover and cook until the broccoli is tender, about 12 minutes. Stir in thyme and salt. Puree the soup with an immersion blender until smooth, about 2 minutes. (Alternatively, transfer soup, in batches if necessary, to a blender. Remove center piece of blender lid to allow steam to escape; secure lid on blender. Place a clean kitchen towel over opening in lid. Process until smooth, about 2 minutes. Use caution when blending hot liquids.) Add half-and-half and process just until incorporated, about 15 seconds. Serve immediately, topped with chives.