Directions
Preheat the oven to 425°F (220°C). Slice off both ends of the squash, then cut the squash in half lengthwise. Scoop out and discard the seeds and stringy flesh. Cut each half in 3 or 4 pieces. Choose a baking dish just large enough to hold the squash and fennel and coat the bottom with the 1 tablespoon olive oil. Arrange the squash and the fennel in the baking dish cut side down, cover tightly with aluminum foil, and bake until a knife pierces the squash easily, about 45 minutes. Let cool, then scoop the squash flesh out of the skin and discard the skin. Chop the fennel roughly.
In a large, heavy pot, melt the butter over medium-low heat. Add the onion and sauté until soft and sweet, about 10 minutes. Add the thyme and cook 1 minute. Add the squash, the fennel, and 4 cups (1 l) broth. Bring to a simmer and cook gently for 5 minutes. Puree in a blender, in batches if necessary. Return to the pot and reheat, thinning with broth to the desired consistency. The soup should not be thick. Season with salt and pepper.
Prepare the fried sage: In a very small skillet, melt the butter with the oil over medium-low heat. Add the sage leaves and cook slowly, turning with tongs, until they darken and begin to crisp, about 5 minutes. Drain on paper towels and sprinkle with salt. You can prepare the sage leaves up to 2 hours ahead.
Put the crème fraîche in a bowl and, if necessary, thin with water until you can drizzle it with a whisk. Divide the hot soup among 6 bowls, then drizzle each portion with some of the crème fraîche and garnish with 2 fried sage leaves. Serve immediately.
Recommended Pairings
California Merlot or California Chardonnay