Preheat the oven to 180°C (356°F).
Wash the blueberries thoroughly and set aside.
Combine oat flour, almond flour, and baking powder in a bowl and mix well.
Add eggs, Greek yogurt, and erythritol. Mix until evenly combined.
Gently fold the blueberries into the batter.
Pour the batter into a cake mold and spread it evenly.
Bake in the preheated oven for 30–35 minutes.
Let cool, then decorate with additional blueberries and yogurt as desired.