Fennel is an underrated and under-utilized vegetable in this country, but its devotees (especially in Italy) prize its subtle anise taste and versatility, whether raw or cooked. Here we've paired it with crystallized ginger in an intriguing, velvety soup. Use our recipe for Candied Ginger Purée if you'd like to make your own version of this popular condiment; otherwise, use your food processor to pulverize cubes or slices of crystallized ginger for this recipe. For a nice garnish, save some of the feathery fennel fronds, if possible.
Cut the fennel bulbs in half lengthwise (through the stem end). Cut out and discard the hard white core at the bottom of the bulb. Slice the bulbs crosswise into thin slices (the thinner the slices, the faster the fennel will cook).
Place the butter in a heavy-bottomed pan and melt over medium heat. Add the shallots and fennel; cook, stirring occasionally, until the mixture is hot. Add 3 cups of the chicken stock and cover the pan. Cook until the fennel and shallots are very tender, about 20 minutes. Remove from the heat, uncover, and let rest for 10 minutes.
Meanwhile, brush off as much of the sugar from the crystallized ginger as you can. Place the ginger in a food processor and pulse to finely chop it. Add the fennel mixture and purée until the soup is smooth.
Return the purée to a clean saucepan and add the ground fennel seed and heavy cream. Add salt and pepper to taste. If the soup is too thick, add some of the remaining stock. Reheat gently until hot.
Divide among 4 bowls and garnish each serving with a sprig of fennel frond, if using.