for the donuts

1. Heat the oven to 350℉. Spray 2 doughnut pans with nonstick cooking spray. Set aside.
2. In a small bowl, mash the banana with the back of a fork until smooth. Set aside.
3. In a large mixing bowl, whisk together the flour, cocoa powder, espresso powder, baking powder, baking soda, salt, and nutmeg until combined. Set aside.
4. In a medium saucepan over medium heat, melt the butter. Remove from the heat, add the chocolate chips, and stir constantly with a spatula until melted. Stir in the mashed banana, brown sugar, egg, buttermilk, and vanilla, one at a time, mixing thoroughly after each addition.
5. Pour the chocolate mixture over the dry ingredients, then gently stir together until just combined. Be careful to not overmix.
6. Scoop the batter into a piping bag, and pipe the doughnut batter into the doughnut pans, filling each doughnut mold about halfway full.
7. Bake for 12 to 15 minutes, until the doughnuts are firm and slightly springy to the touch. Remove from the oven, and let cool in the doughnut pans for 5 to 10 minutes. Carefully invert each doughnut from the pan, transfer to a baking rack, and let cool completely before glazing.

for the espresso-chocolate glaze

1. In a medium mixing bowl, sift together the powdered sugar and cocoa powder until no lumps remain.
2. Whisk in the espresso until well combined. Add more or less espresso until the glaze reaches your desired consistency. The glaze should be thick but still pourable. Stir in the vanilla and corn syrup, if using.
3. Glaze the doughnuts by dipping the top half of each into the glaze, letting any excess glaze drip back into the bowl. Place on a baking rack, sprinkle with chopped nuts or chocolate sprinkles, and allow the decorated doughnuts to set up for a few minutes before serving. Enjoy!!