Drain the beans. Place in large soup pot with stock and bay leaf and bring to a boil.
Skin off the foam and reduce heat. Simmer for 1 hour.
In a small skillet heat olive oil and sauté the leeks until they begin to soften. Add the minced garlic and cook for another 5 minutes.
Add leeks and garlic to beans, along with diced roasted pumpkin. Mix all ingredients and continue to simmer until beans are soft -- about 30 minutes.
Remove bay leaf.
Ladle soup into food processor or blender and blend until smooth. You'll need to do this in 2 or 3 batches. I like to reserve some of the beans and pumpkin whole for a little texture.
Return to pot. Stir in slivered sage. Add celtic salt and fresh ground pepper to taste.
Serve hot with slivered sage for presentation.