Shaped like a flattened drum, buttercup squash most closely resembles the local squash used in this comforting hearty soup from northern Brazil. It has a dark green peel, a grayish turban-shaped top and dense orange flesh. Hubbard, butternut or delicata squashes could also be used. Instead of the lip-numbing Brazilian green jambu, we have used spinach. For a more festive look, serve in a roasted squash half (see Tip).