Heat the oil in a large soup pot or Dutch oven over medium low heat. Add the leeks and sauté until soft, about 4 minutes. Add the garlic and cayenne pepper and sauté 30 seconds longer.
Add the butternut squash and potato, and sauté 1 minute more. Increase the heat to medium, then add the bay leaf and broth and bring to a boil.
Reduce heat to medium low and simmer for 20 minutes, or until the squash and potato are very tender. Remove from heat and discard the bay leaf.
Puree the soup with an immersion blender or high speed blender until smooth.
Stir in the cream and season with salt and pepper, to taste. Serve and enjoy!