Roasted Kabocha Squash Soup with Ginger Butter
1 kambocha or other Winter squash, about 3 ½ pounds
1 tablespoon butter
1 tablespoon olive oil
2 leeks, white and light green parts only, cleaned and roughly chopped
1 thick (about ¼ inch) slice Prosciutto di Parma, cut into ¼-inch cubes (see Note)
5 cups vegetable broth
1 ½ cans (2 ¼ cups) coconut milk
¾ teaspoons ground cardamom
¾ teaspoons ground coriander seed
2 tablespoons minced ginger
3 tablespoons butter, at room temperature
Heat the oven to 375 F. Line a baking sheet with parchment paper or aluminum foil and lightly oil the paper. Cut the squash in half, scoop out the seeds. and lay the squash halves cut side down on the paper. Bake until very tender and the cut sides are well browned, about 1 hour. Cool to room temp.
Scoop out the squash from the skin or, if it is easier, peel the skin from the roasted squash. Set aside.
Heat the butter and oil over medium heat in a heavy 6-quart soup pot. Add the leeks, cover, and cook, stirring occasionally, until the leeks are wilted and soft, about 8 minutes.
Stir the broth into the leeks and add the squash, coconut milk, cardamom and coriander. Bring to a boil. Adjust the heat to simmering, add salt and pepper to taste and cook until the leeks are tender, about 10 minutes.
Zest one of the oranges and juice them both. Stir the juice into the soup.
Make the ginger butter. Heat 1 tablespoon of the butter in a small skillet. Add the ginger and cook until fragrant. Cool and then stir into the remaining softened butter along with the orange zest.
Puree the soup in a blender or using an immersion blender until very smooth. Season, adding salt and pepper as needed. Ladle into warm soup bowls and float a slice or two of ginger butter over each serving.
Note: Often, markets will sell slices from the shank end of the prosciutto at a considerably lower price than those from the wider end of the ham. It is worth asking.