Step 1

Melt butter in a large Dutch oven over medium-high heat. Add fennel, leek and celery; cook, stirring occasionally, until softened, about 5 minutes. Add garlic; cook, stirring often, until softened and fragrant, about 1 minute.

Step 2

Add potatoes, broth, water and salt; bring to a boil over high heat. Reduce heat to medium-low; cover and simmer, stirring occasionally, until the potatoes are very tender when pierced by a fork, about 25 minutes. Remove from heat.

Step 3

Working in 2 or 3 batches, ladle the soup into a blender. Secure the lid on the blender and remove the center piece to allow steam to escape. Place a clean towel over the opening. Pulse until desired consistency, 10 to 12 pulses. (Use caution when blending hot liquids.) Return the blended mixture to the pot.

Step 4

Add half-and-half and Worcestershire to the potato mixture; stir to combine. Divide the soup among 6 bowls. Sprinkle with parsley and pepper and serve.