Preheat the oven to 170°C (338°F).
Soften the cream cheese until smooth.
Add Greek yogurt, sugar, and vanilla extract, and mix well.
Add eggs and whisk thoroughly.
Sift in cocoa powder and cake flour, then mix.
Melt the chocolate using a double boiler.
Add the melted chocolate and melted butter to the batter, and mix evenly.
Pour the batter into a mold and smooth out the surface.
Bake in the preheated oven for 30–35 minutes.
After it cools completely, chill in the refrigerator for at least 2 hours to set.