01 -
Warm your oven to 350°F. Cover a 9x5-inch bread pan with cooking spray.
02 -
Mix up flour, bicarb soda, and salt in a bowl. Give it a quick stir with a fork. Put it aside for now.
03 -
Using your mixer, beat the butter with both sugars on medium-high speed until they're completely mixed, taking about 1-2 minutes.
04 -
Add your eggs, vanilla, and bananas, mixing until you've got just a few banana chunks left. Don't forget to scrape down the sides.
05 -
Add the flour mix and sourdough starter, stirring by hand just until combined.
06 -
Dump the batter into your greased pan. Let it bake for 55-65 minutes until a toothpick shows moist crumbs but no raw batter. Let it sit for 10 minutes before slicing.