Break the chocolate into pieces.
Melt butter and dissolve chocolate in it while stirring.
Preheat the oven to 200 °C.
Whisk eggs a little, then add sugar, flour, cinnamon and baking powder and beat the mixture well.
Line a baking tray with baking paper, spread the mixture evenly on it and bake the cake for at least 20 minutes (test with a stick).