Chocolate Macarons

For the macarons:

gm blanched slivered almonds

gm minus 2 tbsp. confectioners’ sugar

cocoa powder (Dutch-process preferred)

gm egg whites (from about 3 eggs), aged at room temperature for 12-24 hours

gm granulated sugar

For the espresso ganache:

heavy cream

unsalted butter

granulated sugar

bittersweet chocolate, finely chopped

espresso powder