From Jean François Meteigner at La Cachette
2 pounds butternut squash
2 tablespoons olive oil
1 large onion, cut into 1/2-inch dice
1 medium leek, sliced and washed twice
4 ears corn, shucked and kernels removed
2 branches rosemary
1 teaspoon salt
4 cups chicken or vegetable broth
1. Peel the butternut squash and cut it into half-inch dice.
2. Heat the olive oil in a 6-quart stock pot. Sauté the onion and leek over medium heat about 5 minutes, until just soft. Add the butternut squash and corn and sauté for an additional 10 minutes. Add the rosemary and salt. Cover the vegetables with chicken or vegetable broth and cook uncovered for 30 minutes over low heat.
3. Strain and set aside half the stock; remove the rosemary branches. Purée the vegetables with an immersion or regular blender. Strain the purée through a large mesh strainer to remove the corn skin. Add half a cup of reserved stock (or more, if you prefer a thinner soup) back into the purée mixture. Store overnight in the refrigerator and reheat before filling an insulated container.