If using coconut oil, melt it now and let it come to room temperature. (If using canola oil, skip this step.)
Preheat the oven to 325 degrees F. Line a standard muffin pan with paper or silicone muffin cups, then lightly coat the cups with nonstick spray.
In a large mixing bowl, whisk together the whole wheat flour, cocoa powder, baking soda, baking powder, espresso powder, and salt. Set aside.
In a mixing bowl, add the mashed banana (if you are mashing the banana directly in the mixing bowl, double check that you have the correct amount), then whisk in the eggs, milk, honey, brown sugar, vanilla, and oil. If the oil resolidifies, warm the bowl in the microwave in 10-second bursts, just until it melts.
Make a well in the center of the dry ingredients and pour the wet ingredients into it. With a rubber spatula or wooden spoon, stir gently and patiently to combine. The batter will look dry at first but will begin to come together as you go. It will also be thick and shaggy, which is just right. Stop as soon as the dry ingredients disappear and don’t over mix. Fold in the chocolate chips.
Scoop the batter into the prepared muffin pan; the cups will be quite full and the tops will dome when the bake. Sprinkle with extra chocolate chips if desired.
Bake the muffins for 22 to 26 minutes, or until a toothpick inserted in the center of a muffin in the center of the pan comes out clean without any wet batter clinging to it. Test a few times to make sure the muffins are cooked through (and that what stuck to the toothpick was in fact batter and not a melted chocolate chip).
Remove the muffins from the oven and place them on a wire rack. Let cool in the pan for 3 minutes. Then, using a dull knife or fork to help you out, gently remove the muffins from the pan, allowing them to cool for about 15 minutes on a rack before peeling off the muffin papers. Enjoy!
TO MAKE GLUTEN FREE: Use a 1:1 all purpose GF baking blend like this one.
TO MAKE DAIRY FREE: Use a non-dairy milk, such as almond milk
TO MAKE VEGAN: **Not yet tested. This is my best estimate.** I believe you could swap flax eggs for the regular eggs, use non-dairy milk, and swap maple syrup for the honey. If you decide to try this, I'd love for you to report back in the comments.
Yield: 14 muffins is based on the standard 12-cup muffin pan I used to make this recipe. Different brands can vary a bit based on size (even when they have room for 12!). Fill the muffin cups almost all the way to the top, and if you have a few extra (or a few less), don't worry. You're still getting the same amount of delicious muffin bites!