01 -
Preheat the oven to 425°F with a rack positioned in the upper third. Line a standard muffin tin with paper liners and lightly coat the entire pan, including the top and muffin cups, with nonstick cooking spray.
02 -
If using Nutella, line a plate with plastic wrap. Place 12 small tablespoons of Nutella on the plate and freeze until ready to use.
03 -
In a medium bowl, whisk together the flour, brown sugar, granulated sugar, baking powder, baking soda, and salt.
04 -
In a large bowl, combine the hot coffee, butter, and cocoa powder. Let sit for a minute to melt the butter, then whisk until smooth. Whisk in the eggs, one at a time, until fully incorporated.
05 -
Gradually add the dry ingredients to the wet ingredients. Stir with a whisk until no pockets of flour remain. The batter will be smooth and thin.
06 -
Divide half of the batter evenly among the muffin cups. Sprinkle ¾ cup of the chocolate chunks and add Nutella, if using, to each cup. Pour the remaining batter over the top, filling to the edges. The chocolate chunks will sink into the batter.
07 -
Bake the muffins for 15 to 18 minutes, or until the tops are crackly and a toothpick inserted in the center comes out with a few crumbs. Avoid overbaking to keep the muffins moist. Cool in the pan to let carryover cooking finish.
08 -
While the muffins are still warm, gently press the remaining ¾ cup of chocolate chunks onto the tops. The chocolate will melt and adhere to the muffins.
09 -
Serve the muffins warm or let cool completely to allow flavors to develop further.