1 large butternut squash, about 3 pounds, halved, seeds removed
2 tablespoons vegetable oil
1/2 teaspoon salt
Freshly ground black pepper
1/2 pound sweet Italian sausage, removed from casings
1 large onion, chopped
6 cloves garlic, minced
1 tablespoon chopped fresh sage, plus 12 whole leaves
1 teaspoon chopped fresh marjoram
6 cups light chicken stock or broth
1 teaspoon cider vinegar or lemon juice
1/2 cup heavy cream, or more to taste
2 tablespoons butter
Preheat the oven to 400 degrees F.
Lightly coat the squash halves with 1 teaspoon of the vegetable oil. Season the inside with salt and pepper and place cut-side down on a baking sheet lined with foil. Fill bottom of baking sheet with ¼” of water. Bake until very tender, about 45 minutes. When the squash is cool enough to handle, scoop out the flesh and reserve. Discard the peel.
Combine the squash and chicken broth. Puree with a hand-held immersion blender, or in batches in a food processor or blender.
In a large saucepan over medium-high heat, add the remaining vegetable oil and, when hot but not smoking, add the sausage. Cook until golden brown, about 4 minutes. Add the onions and cook, stirring, until the onions wilted and starting to caramelize, about 6 minutes. Add the garlic, spinach, sage and marjoram, and cook, stirring, for 1 minute. Add the pureed squash and chicken stock, stir well to combine, and bring to a boil. Reduce the heat to low, and simmer for 30 minutes, stirring occasionally.
Add the cider vinegar and stir to combine. Add the cream and adjust seasoning, to taste.
In a small saute pan, cook the butter over medium-high heat until it begins to turn brown around the edges. Add the whole sage leaves and cook until crisp, 1 to 2 minutes. Transfer the leaves to paper towels to drain.
Serve the soup in bowls, garnished with the crispy sage leaves.