Preheat oven to 160 C / Gas 3. Line a 20cm square baking tray with baking parchment.
Whisk egg white, coconut sugar and almond extract together in a bowl. Fold ground almonds into egg mixture until just combined; spread mixture into baking tin. Sprinkle almonds over the top and press down lightly.
Bake in preheated oven until golden brown, about 25 minutes. Transfer to a cooling rack using the greaseproof paper to lift it out of baking tray. Cool to room temperature, about 1 hour, then slice into 9 pieces.