Heat oil in large saucepan on medium heat. Add squash, onions and garlic; cook 5 min. or until crisp-tender, stirring occasionally. Stir in allspice; cook and stir 1 min.
Add bouillon and water. Bring to boil; cover. Simmer on low heat 15 min. or until squash is tender. Process, in batches, in food processor until smooth. Return to saucepan; cook until heated through, stirring occasionally.
Ladle into 8 bowls. Top with sour cream.