In a large bowl or using a stand mixer fitted with the paddle attachment, combine butter, cream cheese, sour cream, and both sugars. Stir or mix until the mixture is light and fluffy.
Add eggs and vanilla extract to the mixture and mix until well combined. Set aside.
In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt.
Add dry ingredients to the cream mixture and stir until they are fully combined. Gently fold in the chopped chocolate.
Divide the dough into 12 balls and place them 2 inches apart on a parchment-lined cookie sheet. Press each ball to flatten
slightly.
Bake for 12-13 minutes, or until the cookies are set.