large egg
Cooking spray
ripe bananas
black sesame paste, black sesame butter, or black tahini, well-stirred
kosher salt
all-purpose flour
buckwheat flour
baking soda
granulated sugar
toasted sesame oil
vegetable oil
black or white sesame seeds
Place 1 large egg in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Let sit until room temperature.
Arrange a rack in the middle of the oven and heat the oven to 375ºF. Coat a 9x5-inch loaf pan with cooking spray. Line the bottom and 2 long sides of the pan with a sheet of parchment paper that extends past the sides by a few inches to form a sling.
Peel 2 large or 3 small ripe bananas, place in a medium bowl, and mash with a fork or potato masher until mostly smooth (about 1 heaping cup). Make a well in the center of the bananas. Place 1/4 cup black sesame paste and 1 teaspoon kosher salt in the well and stir to combine.