Parsley-Root Soup with Truffled Chestnuts

PreparationMake soup: Cook onion and garlic in butter in a large heavy pot over medium heat, stirring occasionally, until onion is softened and golden, 6 to 8 minutes. Add parsley root, thyme, bay leaf, white pepper, and 3/4 teaspoon salt and cook, stirring occasionally, until parsley root begins to soften, 8 to 10 minutes. Add water and broth and simmer, partially covered, until parsley root is very tender, 30 to 40 minutes. Discard thyme and bay leaf and stir in oil. Purée soup in batches in a blender until smooth (use caution when blending hot liquids), transferring to a bowl. If soup is too thick, thin to desired consistency with water. Season with salt, then return to cleaned pot to keep warm, covered, until ready to serve. Shave chestnuts with an adjustable-blade slicer or sharp vegetable peeler as thinly as possible over each serving. Cooks' note:Soup, without chestnuts, can be made 2 days ahead and chilled, uncovered, until cool, then covered. Reheat over low heat, thinning with water if necessary. Shave chestnuts over soup just before serving.

PreparationMake soup: Cook onion and garlic in butter in a large heavy pot over medium heat, stirring occasionally, until onion is softened and golden, 6 to 8 minutes. Add parsley root, thyme, bay leaf, white pepper, and 3/4 teaspoon salt and cook, stirring occasionally, until parsley root begins to soften, 8 to 10 minutes. Add water and broth and simmer, partially covered, until parsley root is very tender, 30 to 40 minutes. Discard thyme and bay leaf and stir in oil. Purée soup in batches in a blender until smooth (use caution when blending hot liquids), transferring to a bowl. If soup is too thick, thin to desired consistency with water. Season with salt, then return to cleaned pot to keep warm, covered, until ready to serve. Shave chestnuts with an adjustable-blade slicer or sharp vegetable peeler as thinly as possible over each serving. Cooks' note:Soup, without chestnuts, can be made 2 days ahead and chilled, uncovered, until cool, then covered. Reheat over low heat, thinning with water if necessary. Shave chestnuts over soup just before serving.