Preheat the oven to 180°C (356°F).
Mix protein powder, almond flour, and baking powder in a bowl.
Add eggs, olive oil, lemon juice, and sweetener; mix evenly.
Pour the batter into a pound cake mold.
Bake for 25-30 minutes at 180°C (356°F).
Allow to cool, then finish by sprinkling lemon zest on top.