In the bowl of a stand mixer, add the granulated sugar and oil. Mix on low speed for 15 seconds until fully combined.
Add the eggs, mashed bananas, buttermilk and vanilla. Mix on low speed for 15-30 seconds until fully combined. Scrape down the bowl and mix another 15 seconds.
Add the gluten free flour, baking soda, and salt. Mix on low speed for 15 seconds. Stop the machine and scrape down the sides. Mix on medium for 30 seconds until fully combined.
Fold in the chopped nuts.
Set batter aside to rest for 30 minutes.
Preheat oven to 350F. Spray the bottom and sides on a non-stick 9"x5" baking pan with cooking spray.
Pour batter into the pan and bake for between 1 hour 20 minutes and 1 hour 30 minutes. Start testing the bread with a toothpick at 1 hour 15 minutes. Cover with foil if top is browning too quickly.
Remove from oven and let cool in the pan on a wire rack for 10 minutes. Remove from the pan to finish cooling completely before slicing.
Notes
Make sure ingredients are at room temperature.
As a substitute for the granulated sugar, Swerve granular sweetener may be used.
A flax or chia egg may be substituted for the eggs.
This recipe uses homemade buttermilk:
Pour 1 Tablespoon of white vinegar in a measuring cup.
Fill the cup to the ½ cup measurement with almond milk.
Test the bread with a toothpick to ensure it is baked all the way through.
Let the bread cool completely before slicing.
Store this bread, wrapped in plastic wrap, on the counter for up to 2 days. After that, slice it and freeze it for longer storage. Defrost slices in the microwave.