Preheat the oven to 170°C (338°F).
Separate the egg whites and yolks.
Add sugar substitute and vanilla extract to the yolks and mix.
Whisk the egg whites into meringue.
Add almond flour and baking powder to the yolk batter and mix.
Gently fold the meringue into the yolk batter in three additions.
Pour the batter into a cake mold and smooth the top.
Bake in the oven for 30 minutes.
Once cooled, cut into desired sizes.