makes about 35
1 cup confectioner's sugar
1/2 cup finely ground unsalted pistachios
1/4 cup finely ground slivered almonds
2 large egg whites, room temperature
1/4 cup superfine sugar
1/2 cup heavy cream
3 1/2 oz dark chocolate, finely chopped
pulse confectioner's sugar, pistachio flour and almond flour in a food processor until combined. sift mixture and if not fine enough to go through, grind again in food processor or spice grinder. whisk whites with a mixer on medium speed until foamy. increase speed to high and whisk until soft peaks form. reduce speed and add sugar. whisk until stiff peaks form and then fold in flour mixture. preheat oven to 300 degrees F. spoon batter into a pastry bag fitted with a 1/2-inch plain round tip. pipe 3/4-inch rounds about 1-inch apart on parchment lined baking sheets. let macaroons stand at room temperature for 15 minutes or until a light crust forms. bake on upper and lower third racks until crisp, rotating halfway through, about 22-26 minutes. cool completely on baking sheets to harden bottoms and remove carefully with a spatula.
meanwhile, bring cream to a boil over medium high heat. pour over chocolate in a heatproof bowl and let sit 2 minutes, covered with a small sheet pan. remove cover and whisk until smooth. let cool and slightly harden before assembling cookies.
sandwich two same size macaroons with 1 tsp chocolate ganache and serve immediately. can be stacked between layers of parchment, wrapped in plastic and frozen for up to three months.