For the soup:
- 1 ounce fresh black truffle
- 2 cups plus 1 1/2 quarts chicken stock
- 3 tablespoons butter
- 3 medium shallots
- 5 ounces Cremini mushrooms, quartered
- 2 pounds roasted and peeled chestnuts, coarsely chopped
- 1 cup apple cider
- Maple syrup to taste
- Cider vinegar
- Salt and white pepper to taste
- Brioche croutons (see below)
For the brioche croutons
- 4 slices brioche, crust removed, 1/4-inch dice
- 3 tablespoons clarified butter
- In a small pot, place the black truffle and 2 cups of chicken stock. Simmer the truffle in the stock for 3 minutes. Remove the truffle and set aside to cool.
- Continue to cook the chicken stock until it is reduced by half, then set aside.
- Meanwhile, in a pot large enough to hold all of the ingredients, melt the butter. Add the mushrooms and shallots and sweat until mushrooms have yielded their liquid and that has evaporated.
- Add the chestnuts, 1 1/2 quarts of chicken stock, the reserved liquid from cooking the truffle, and cider. Simmer the mixture until the chestnuts are tender.
- Strain the chestnuts and reserve the cooking liquid.
- Place the chestnuts in a food processor and process to achieve a creamy consistency, adding cooking liquid as necessary.
- Season to taste with maple syrup, cider vinegar, salt and white pepper. Return to a pot and keep hot.
- Julienne the black truffle.
Serve the soup hot, topped with brioche croutons (below) and julienned truffle.
For the croutons
- In a sauté pan, heat the butter over high heat until it is just about to smoke.
- Add the diced brioche and toss it to cook evenly without burning. Season the croutons with salt and drain on paper towel-lined plate.