Place egg whites in a bowl and whip until foamy.
Add erythritol and protein powder, then gently mix.
Add almond flour and salt, and mix to form the dough.
Transfer the dough to a piping bag and pipe circles onto a parchment-lined baking tray.
Bake in a preheated oven at 170°C (338°F) for 15-20 minutes.
Let cool and serve.