1. Process almonds and 1 tablespoon granulated sugar in a food processor until finely ground. Transfer to a medium bowl; stir in confectioners' sugar. Put egg whites and salt into bowl of mixer fitted with whisk attachment; beat on medium until soft peaks form. Add remaining granulated sugar; beat until stiff peaks form. Mix in vanilla and lemon juice. Fold in almond mixture in 2 batches. Stir in zest.

2. Preheat oven to 300 degrees. Put batter in a pastry bag fitted with a 1 1/2- inch round tip (Ateco tip #803 or #804); pipe 2-inch rounds onto a nonstick baking sheet. Bake until golden and set, about 15 minutes. Let cool on a wire rack.

3. Bring cream to a boil in a pan. Pour over chocolate and espresso in a heatproof bowl; whisk. Transfer to freezer and stir occasionally until thickened, about 6 minutes.

4. Spread 2 teaspoons filling onto bottom of half of the cookies. Sandwich with remaining cookies. Dust with confectioners' sugar.