Instructions

1. 1
   Sift the almond flour and powdered sugar together twice through a fine-mesh sieve into a large bowl; discard any large bits.
2. 2
   In a perfectly clean glass or metal bowl, beat egg whites and cream of tartar until soft peaks form.
3. 3
   Gradually add granulated sugar while beating on high speed until stiff, glossy peaks form.
4. 4
   Fold the dry ingredients into the egg whites in three batches using a rubber spatula.
5. 5
   Cut down the center and sweep around the bowl (the 'macaronage' step) until the batter falls off the spatula in a thick, continuous ribbon resembling molten lava.
6. 6
   Transfer batter to a piping bag fitted with a round tip.
7. 7
   Pipe 1.5-inch circles onto a baking sheet lined with a silicone mat.
8. 8
   Firmly tap the baking sheet against the counter 4-5 times to release trapped air bubbles.
9. 9
   Let the shells sit at room temperature for 45-60 minutes until a dry skin forms and they are no longer sticky to the touch.
10. 10
    Preheat oven to 300°F (150°C).
11. 11
    Bake for 14 to 16 minutes.
12. 12
    Let cool completely before removing from the mat.
13. 13
    Make filling: Bring cream to a simmer, pour over chopped chocolate, let sit for 2 minutes, then stir until smooth.
14. 14
    Let cool until spreadable.
15. 15
    Match identical shells, pipe a dollop of ganache onto one, and sandwich gently with the other.