1. Preheat the oven to 350 degrees F. and butter/oil a standard loaf pan.
2. In a large bowl, whisk the flours with the sugar, the baking powder, and the cinnamon.
3. In a blender, process the bananas with the eggs, the buttermilk, the cooled brown butter and the vanilla.
4. Pour the banana mixture into the flour mixture and combine with a rubber spatula. Fold in the chocolate chips, if using, then transfer batter to your prepared pan.
5. Bake for 55-60 minutes, or until a toothpick inserted in the center of the banana bread comes out clean.
6. If you are going to glaze the bread, mix the powdered sugar, water, and optional cinnamon together with a fork until the desired consistency is reached. Add a bit of water if you want it thinner, or more powdered sugar if you'd like it to be thicker. Set aside and wait to pour it on until the bread has cooled if you want the glaze to set (like in the pictures here); if you want it to seep in, you can glaze the bread while it's hot.
7. Glazed or not, allow some time for the bread to cool before slicing, if possible.