1. Process almonds and 1 tablespoon granulated sugar in a food processor until finely ground.
2. Transfer to a medium bowl; stir in confectioners' sugar.
3. Put egg whites and salt into bowl of mixer and using whisk beat on medium until soft peaks form.
4. Add remaining granulated sugar; beat until stiff peaks form.
5. Mix in vanilla and lemon juice.
6. Fold in almond mixture in 2 batches. Stir in zest.
7. Preheat oven to 300 degrees.
8. Put batter in a pastry bag fitted with a 1 1/2- inch round tip; pipe 2-inch rounds onto a nonstick baking sheet.
9. Bake until golden and set, about 15 minutes. Let cool on a wire rack.
10. Bring cream to a boil in a pan.
11. Pour over chocolate and espresso in a heatproof bowl; whisk.
12. Freeze, stirring, until thick, 6 minutes.
13. Spread 2 teaspoons filling onto bottom of half of the cookies.
14. Sandwich with remaining cookies.
15. Dust with confectioners' sugar.