Preheat the oven to 350℉. Line a 12-cavity muffin pan with paper liners. Set aside for later.
In a large mixing bowl, whisk together the chocolate cake mix, 2 cups of the chocolate baking chunks, cocoa powder, and baking powder.
Add in the eggs and half and half. Stir until combined. Use a rubber spatula to scrape the sides and bottom of the bowl to ensure that all the batter is mixed evenly.
Scoop the muffin batter into each muffin liner, filling each one about 2/3 full with batter.
Sprinkle the remaining chocolate chunks over the top of the muffins.
Bake for 17-20 minutes. The muffins are done when a toothpick comes out without wet batter.
Remove the muffins from the oven and allow them to cool for 5 minutes before removing them to a cooling rack.
Serve warm and enjoy!