Step 1

Melt the butter in a large pot over medium low heat. Add the onions and saute for 10 minutes, or until onion is translucent.

Step 2

Add the celery and the water. Cover and bring to a boil, then reduce heat to low and simmer for 30 minutes, or until celery is soft.

Step 3

Add 2 1/2 ounces of the Stilton cheese to the soup and mix well. Puree the soup in small batches in a blender or food processor and transfer it to a clean pot. Season with freshly ground pepper and salt to taste. Stilton can be very salty, so beware!

Step 4

Pour into individual bowls, sprinkle with the remaining cheese and garnish with the watercress.