Golden Squash and Cheddar Soup

Halve squash lengthwise. Place cut sides down on baking sheet. Bake in 375°F (190°C) oven until tender, about 40 minutes. Remove and discard seeds; scoop out pulp. In 3 quart saucepan, cook leeks in butter over low heat until wilted, about 10 minutes. Add broth, thyme, pepper and squash pulp; mix. Blend until smooth in two batches. Return to saucepan. Bring just to boiling; reduce heat and simmer 5 minutes. Gradually stir in 1 1/2 cups of the cheese. Stir until cheese is melted; do not boil. To serve, ladle in bowls; garnish with sour cream, the remaining cheese and the green onions.