- Cut squash into 3/4-inch cubes.
- Combine basil, rosemary and 1-1/2 cups water in large saucepan or Dutch oven; bring to boil. Add squash; cover and return to boil. Reduce heat; simmer 45 minutes, gently stirring occasionally.
- Reserving 1 cup squash, pour remaining squash and liquid into blender or food processor container. Cover and process until smooth; return to saucepan.
- Blend flour and 1/4 cup water; stir into squash mixture with sherry. Bring to boil; reduce heat and cook until thickened, stirring constantly.
- Slowly pour in milk and less sodium soy sauce until blended. Add reserved squash and cook until heated through.
- Garnish each serving with dollop of sour cream and walnuts.