• 1 medium butternut squash (about 2 pounds)
• 1 tablespoon olive oil
• 1 yellow onion , cut in half and thinly sliced
• 1 stalk celery , thinly sliced
• 1 carrot , thinly sliced
• 1 teaspoon fresh rosemary leaves
• 2 cups chicken or vegetable stock
• 3/4 cup milk or cream
• 1 1/2 teaspoons kosher salt
• 1/4 teaspoon freshly ground pepper

Peel squash and remove seeds. Cut into 1 1/2-inch chunks and set aside.

Add oil to a 4-quart saucepot and place over medium heat. Add onion, celery, carrot, and rosemary, and cook until onion begins to brown, stirring occasionally, about 15 minutes.

Add squash, stock, and 1 cup water. Bring to a boil, then reduce to a simmer and cook until squash is tender, about 15 minutes. Turn off heat and let soup cool slightly, about 8 minutes.

Using a standard or immersion blender, puree soup until smooth. If using a standard blender, puree in small batches to prevent spillage. Transfer to a clean pot or storage container. Soup can be refrigerated for up to 2 days or frozen for up to 2 months.

When ready to serve, reheat. Add milk, salt, and pepper; stir well. Add additional milk or stock if soup is too thick; simmer 5 minutes. Adjust seasoning to taste, and serve warm.