Preheat oven to 300 degrees and line 2 baking sheets with parchment paper.

Sift together powdered sugar, cinnamon, cloves, ginger and cornstarch and set aside.

In a double boiler or a metal bowl set over a pot of boiling water, whisk together egg whites and granulated sugar until mixture is warm and sugar has dissolved. Be careful not to overheat, as egg whites will cook and congeal. You only need to do this until the mixture is warm (doesn’t take long)

Remove from heat, add cream of tartar and salt and beat with electric mixer until egg whites hold stiff peaks, about 3 minutes. Add vinegar and mix just until incorporated.

Gently fold in reserved powdered sugar mixture, white chocolate chips and nuts.

Drop by large tablespoonfuls onto parchment-lined baking sheets and bake for 30 minutes. Remove from oven and let cool on a rack.

Makes about 24 cookies which are crusty on the outside and chewy in the middle.