How to Make It
In a small bowl, soak the dried cherries in the kirsch for 1 hour; drain.
Meanwhile, preheat the oven to 400°. Spread the nuts on a baking sheet and toast them for about 5 minutes, stirring once, until golden brown. Let cool completely, then pulse nuts in a food processor until coarsely chopped. Reduce the oven temperature to 325°. Line a baking sheet with parchment paper.
In a medium bowl, combine 1/4 cup of the granulated sugar with the brown sugar. Add the butter and beat with an electric mixer until smooth. Beat in 2 of the egg whites and the vanilla until the mixture is creamy. Beat in the flour, then stir in the nuts and the drained cherries until evenly distributed; the dough will be soft and slightly sticky.
Working on a sheet of wax paper, shape the dough into a 14-inch log. Roll the log onto the line baking sheet. Beat the remaining egg white and brush it on the log. Sprinkle with the remaining 2 teaspoons of granulated sugar. Set the baking sheet on a second baking sheet and bake in the middle of the oven for about 1 hour, or until the log is golden and firm to the touch. Let cool on the baking sheet, about 3 hours or overnight.
Using a sharp serrated knife, carefully cut the log on a diagonal into 1/4- to 1/3-inch-thick slices. Using a spatula, lay the slices on 2 baking sheets and bake for 10 minutes, or until lightly colored. Gently turn the biscotti and bake for 10 more minutes. Let cool on the baking sheets