Preheat the oven to 250°F. Add the butter, cream cheese, and milk to a saucepan and heat everything. Separate the eggs, add the yolks, flour, and corn starch to the mixture in the saucepan, and whisk everything until combined. Beat the egg whites with the sugar until frothy and gently fold into the mass on the stove. The mass should be creamy and not develop any bubbles.
Take 4 tbsp of the mixture and pour it into 2 small bowls. Pour the rest of the batter into a cake pan lined with parchment paper. Take a wooden skewer to slide through the batter and then let the pan drop twice from a low height onto the work surface to get rid of any remaining bubbles in the batter.
Color one of the small bowls with cocoa powder and the other one with hot cocoa mix so you get one dark and one light brown batter.
Spoon both brown batters into separate piping bags and pipe a leopard spot pattern onto the surface of the light batter in the cake pan.
For this next step, you're going to need a deep sheet pan. Fill it with water and then place the cake pan in the water bath. Put the cake in the oven and bake it at 250°F for 20 minutes. Then raise the temperature to 300°F and bake for another 15 minutes.
After 15 minutes of baking, open the oven door, leave it open for about 10 seconds, and then close it again. Lower the oven temperature to 200°F. Then bake the cake for another 40 minutes. After 40 minutes, turn off the oven, open the door, and allow the cake to cool down in the open oven for 10 minutes.
