Preheat the oven to 180°C (356°F).
In a bowl, mix oat flour, cocoa powder, and baking powder.
In another bowl, whisk together eggs, Greek yogurt, unsweetened almond milk, and erythritol.
Combine the two mixtures and mix well.
Pour the batter into a cake pan lined with parchment paper.
Bake in a 180°C oven for 20-25 minutes.
Let it cool completely, then cut into desired sizes.