Preheat the oven to 170°C (338°F).
Separate the egg whites from the yolks.
Add protein powder, almond flour, erythritol, and milk to the yolks and mix well.
Add a pinch of salt to the egg whites and whip into a meringue.
Gently fold the meringue into the yolk batter in 2-3 additions.
Pour the batter into the mold and top with sliced almonds.
Bake in the preheated oven at 170°C (338°F) for 25 minutes, then let cool.
Divide into 10 pieces and serve one piece.