"Do you have guests you would like to impress? This is the best pumpkin soup I have ever tasted. It is so good it leaves you with a craving that lasts for weeks! Wonderful to serve for the holidays. I like to serve this soup in hollowed-out individual pumpkins for a special presentation."
Melt butter in a large pot over medium heat. Cook and stir onion and leek in melted butter until onion is soft and translucent, about 5 minutes. Add chicken broth, pumpkin puree, curry powder, salt, white pepper, ground ginger, and bay leaf to onion mixture; bring to a boil.
Reduce heat to low and simmer, stirring occasionally, for 15 minutes. Remove from heat to cool. Pour broth mixture into a blender no more than half full. Cover and hold lid down; pulse a few times before leaving on to blend. Puree in batches until smooth. Return pureed mixture to pot and bring to a boil.
Gradually stir half-and-half into pumpkin mixture; cook until soup is heated through, 5 to 10 minutes.