01 -
Heat the oven to 350 degrees F. Grease a 9x5-inch loaf pan and line it with parchment, leaving overhang on the long sides.
02 -
Mash the bananas in a large bowl until mostly smooth. Measure 1 1/2 cups so the loaf has enough moisture without turning gummy.
03 -
Whisk the Greek yogurt, eggs, oil, brown sugar, granulated sugar, and vanilla into the mashed bananas until smooth and glossy.
04 -
In a separate bowl, whisk the flour, baking soda, baking powder, salt, and cinnamon until evenly combined.
05 -
Add the dry ingredients to the banana mixture and fold gently until only a few streaks remain. Fold in 1/2 cup of the walnuts.
06 -
Scrape the batter into the pan and sprinkle the remaining walnuts on top. Bake for 55-65 minutes, tenting with foil if the top browns early, until a toothpick comes out with moist crumbs.
07 -
Cool in the pan for 15 minutes, then lift out with the parchment and cool completely on a rack before slicing.