Position oven racks in the upper and lower third of the oven. Preheat oven to 350º F. Line 2 baking sheets with parchment.

Melt half the chocolate in a double boiler. Remove from heat and allow to cool until luke warm-about 10 minutes.

In a medium mixing bowl, mix together 1/4 cup sweetener, cocoa powder and xanthan gum to blend.

In a separate medium bowl, using electric mixer, beat egg whites until soft peaks form. Add the cream of tartar, 1 tablespoon granulated sweetener, and vanilla. Beat at high speed until stiff peaks form.

Gradually, in small amounts at a time, add the cocoa mixture to the egg whites, beating with the mixer after each addition. Fold in melted chocolate, then fold in nuts and reserved chopped chocolate.

Drop batter on the prepared cookie sheet in rounded tablespoon amounts.

Bake 7 minutes, then reverse sheets and bake for approximately 6-7 minutes more or until set and tops are less shiny. They should have some stability when lightly touched.

Allow cookies to cool on baking sheet for 1 minute, then carefully remove from the sheet and place on a cooling rack.