Instructions

1. 1
   Combine the almond flour and icing sugar. Sift to remove lumps, and set aside.
2. 2
   Add the superfine sugar to the egg whites, and whip them to stiff peaks.
3. 3
   Add the food coloring to the egg whites and continue beating until incorporated.
4. 4
   Use a wooden spoon or rubber spatula to fold the almond flour mixture into the meringue in 3 batches. Mix until you get a lava-like batter (see notes).
5. 5
   Transfer the batter to a pastry bag fitted with an 8 mm round nozzle. Pipe 3 cm rounds on a baking sheet lined with baking paper.
6. 6
   Tap the sheet lightly on your work surface to even and flatten the mixture. Leave to air-dry for 30 minutes until a film forms on the surface of the cookies.
7. 7
   Bake for 12 minutes at 150°C with convection.
8. 8
   Remove from the oven and let cool completely. It's a good idea to move the parchment onto a cooling rack to avoid carryover cooking.
9. 9
   Peel the shells from the parchment, and sort them into pairs of equally sized shells.
10. 10
    Sandwich the cookies together with your desired filling.