- 1 1/4 cups flour
- 1/2 teaspoon baking soda
- 1/2 teaspoon kosher salt
- 1/4 teaspoon baking powder
- 1/2 cup (1 stick) unsalted butter
- 1 cup firmly packed dark brown sugar
- 1 1/2 teaspoon vanilla extract
- 1 teaspoon espresso powder
- 1 large egg
- 3/4 cup dark chocolate, chopped
- 1/2 cup peeled hazelnuts, chopped
Preheat the oven to 350° F. In a medium-sized bowl, whisk together the flour, baking soda, salt, and baking powder.
Heat the butter in the 10-inch cast-iron skillet over medium-low heat. Once the butter has completely melted, add the brown sugar and whisk together until it dissolves, about 1 minute. Slowly pour the butter mixture into the flour mixture. Add the egg, vanilla, and espresso powder. Mix with a wooden spoon until combined.
Fold the chopped chocolate and hazelnuts into the dough. Transfer the dough back to the buttery skillet, and bake for 12-18 minutes or until a toothpick comes out of the center clean.