In a large saucepan, mix the pumpkin, vegetable broth, heavy cream, garlic powder and onion powder. Bring to a boil. Stir in the pasta. Cook 12 minutes, or until pasta is tender but firm. Reduce heat to simmer.
Stir in pumpkin pie spice, parsley and cilantro. Slowly stir butter, plain yogurt and sour cream into the mixture, making sure they do not curdle. Stir in the cheese, allowing it to melt.