Preheat the oven to 350F. Line a standard muffin tin with parchment paper cups.
In a large bowl, mash the bananas. Whisk in the olive oil, eggs, and vanilla until combined. Add buckwheat, almond flour, cinnamon, baking soda, and salt and stir until combined. Stir in ½ cup of chocolate chips or walnuts until evenly distributed.
Scoop the batter into the muffin cups, filling them to the brim. Top with remaining ½ cup chocolate chips or walnuts. Gently press them into the muffin batter so they stick better.
Bake for about 20-25 minutes, or until a toothpick, cake tester, or knife comes out clean (20 minutes was the sweet spot for me).
Enjoy these warm or slice in half and top with butter, honey, and a sprinkle of salt!