Put the oatmeal in a bowl and soak it with milk.
Melt the chocolate using a double boiler or microwave.
Add the egg, melted chocolate, cocoa powder, and baking powder to the oatmeal and mix well.
Pour the batter into an oven-safe pan.
Bake in a 180°C oven for 20–25 minutes.
Let it cool and remove the finished cake.