Line two 18 cm square frames with silicone mats and spray with release agent.
Preheat the oven to 200°C (fan-assisted).
Melt the butter and set aside.
In a stand mixer bowl, combine powdered sugar, almond flour, flour, and salt (pre-sifted).
Add eggs and orange zest. Whisk at high speed for 4–5 minutes until airy.
In another bowl, whip egg whites, gradually adding sugar in 2–3 stages until you get a shiny soft meringue.
Fold a spoonful of the egg mixture into the melted butter, then return it to the batter. Mix gently.
Now fold in the meringue in 2–3 additions using a spatula, keeping the mixture light.
Pipe 165 g into each frame and spread evenly.
Bake for 10 minutes.
Remove and flip onto clean baking paper, then peel off the mats carefully.
Cool completely.
Cut two 16 cm discs with a ring cutter and set aside.