Pre-heat oven to 350F. Grease a 9x5 inch loaf pan with coconut oil and sprinkle with cocoa powder and flour. Set aside.
In a medium bowl, combine the flours, cocoa powder, espresso powder, baking powder, baking soda, salt, and chocolate chips. Set aside.
In a large bowl, whisk the egg, vanilla extract, coconut oil, greek yogurt, honey, and bananas. Add the dry ingredients and mix with a spoon until fully incorporated (do not over-mix).
Pour batter into greased loaf pan and bake for 45-50 minutes or until the top is crusty and the center is set. Cook for at least 10 minutes before slicing.
Notes
* To make oat flour: blend fashioned or quick oats in a blender until they resemble flour. Measure oat flour for the recipe after it's blended.