How to bake a marbled coffee-cake:

1. The Espresso Part:

   • Pour hot coffee over cocoa powder and small chocolate chunks, stirring the mixture to facilitate melting.
   • If the chocolate isn't fully melted, microwave it for 30 seconds.
   • Once the mixture has cooled, add half of the sour cream and thoroughly combine it.

2. Butter and Sugar:

   • take butter + sugar and add it to a bowl.
   • mix  until creamy.
   • add in the eggs (one at the time)

3. Marbelous:

   • Combine flour and baking soda in a separate bowl.
   • Add the melted chocolate-sour cream mixture to HALF of the creamy butter and mix until combined. Then, add half of the flour and mix again.
   • In a separate bowl, mix half of the sour cream with the remaining butter mixture and add the rest of the flour as well as the vanilla extract. Mix until combined.
   • You should now have two batters, one chocolate and one vanilla.
   • Use a generous tablespoon to drop dollops of each batter into the prepared pan in a checkerboard-like pattern until you've used all of the batter.
   • Bake at 180°C for 45 minutes.
   if you are using a bundt-cake pan - make sure to grease butter all over it and cover it with cocoa powder. after that you can add in the cake-batter.