01 -
Preheat the oven to 375°F. Line a standard muffin tin with paper muffin cups.
02 -
In a large bowl whisk together the flour, brown sugar, granulated sugar, cocoa powder, baking powder, baking soda, and salt.
03 -
In a small bowl, combine the melted butter, sour cream, milk, eggs, and vanilla. Pour the butter mixture into the flour mixture and stir until a thick batter forms. Stir in the chocolate chunks. Do not overmix.
04 -
Divide the batter evenly among the muffin cups.
05 -
Bake for 20 minutes, or until a cake tester inserted into the center comes out clean. Transfer the pan to a wire rack to cool for 5 minutes before removing the muffins to the rack to cool completely.