Melt chocolate using a double boiler.
In a bowl, combine Greek yogurt, eggs, and sugar, and mix well.
Add the melted chocolate and mix.
Sift cake flour and cocoa powder into the mixture and combine.
Pour the batter into a mold and smooth the surface.
Bake in a preheated oven at 180°C for 20 to 25 minutes.
Let it cool completely, then refrigerate for at least 1 hour.
Cut into pieces and serve.