Roasted Hubbard Squash Soup with Hazelnuts and Chives

Position a rack in the center of the oven and preheat to 400 degrees F (200 degrees C). Line a heavy-duty rimmed baking sheet with parchment paper.

Combine olive oil, garlic, coriander seeds, fennel seeds, and sage in a mortar; pound with a pestle until consistency is like a coarse paste. Rub spice mixture on the cut-sides of the squash halves. Place squash onto the prepared baking sheet with cut-sides down.

Roast in the preheated oven until tender and easily pierced with a fork, about 1 hour. Remove from oven, turn cut-sides up, and cool until easily handled. Scrape insides of squash into a bowl; you should have about 5 cups.

Melt butter in a 5-quart Dutch oven over medium heat. Add leek, carrots, and a pinch of salt. Cook, stirring occasionally, until leek is softened, 8 to 10 minutes. Add reserved squash, chicken broth, 1 teaspoon salt, and bay leaf. Increase heat to high and bring to a boil. Reduce heat to low, cover, and cook until soup's flavor has developed, about 30 minutes.

Remove and discard bay leaf. Fill blender halfway with soup. Cover and hold lid down with a potholder; pulse a few times before leaving on to blend. Pour into a pot. Repeat with remaining soup. Add lemon juice and season with salt and pepper. Garnish with hazelnuts, chives, and Espelette pepper.