Created by Mikekey on November 29, 2013
Step 1: Trim and discard root ends and coarse tops from leeks. Cut leeks in half lengthwise and rinse under running water, flipping layers to flush out grit; drain, then thinly slice crosswise.
Step 2: Rinse fennel. Trim off and discard root ends and stalks; reserve 2 or 3 sprigs of feathery green tops for garnish. Chop fennel heads.
Step 3: In a 6- to 8-quart pan over medium heat, melt butter. Add leeks and chopped fennel heads, cover, and stir occasionally until vegetables are very tender, 10 to 12 minutes.
Step 4: Scrub potatoes and cut into 1/2 to 3/4-inch cubes.
Step 5: Add broth and bay leaf to pan. Bring to a boil over high heat.
Step 6: Add potatoes to broth mixture and return to a simmer; reduce heat, cover, and simmer, stirring occasionally, until potatoes are tender when pierced, 15 to 20 minutes.
Step 7: In a bowl, whisk milk, flour, 1/2 teaspoon salt, and 1/8 teaspoon pepper until smooth. Add to potato broth mixture and stir over high heat until boiling, about 5 minutes. Add more salt and pepper to taste.
Step 8: Serve in deep bowls. Garnish with reserved fennel sprigs and chives.