Whole Wheat Sourdough Banana Bread takes the classic comforting flavors of banana bread and combines it with the nutrition of whole grains with the tangy character of sourdough.
Preheat the oven to 350F (175C). Grease a 9 by 5 inch loaf pan, or line two 12-cup muffin tins with papers.
Peel the ripe bananas into a large mixing bowl and mash them with a fork until mostly smooth.
Add the olive oil, brown sugar, vanilla, salt, and eggs to the bananas. Stir until evenly combined.
Add the sourdough discard and stir briefly. It will not fully incorporate, and that is fine.
In a separate bowl, whisk together the whole wheat flour, cinnamon, baking powder, and baking soda.
Add the dry ingredients to the wet and fold just until no dry flour remains. The batter will look shaggy and will thicken as it sits. Do not overmix.
Pour the batter into the loaf pan, or divide between muffin cups filling each about three quarters full. Sprinkle turbinado sugar over the top if using.
Bake muffins for 25 to 30 minutes. Bake a loaf for 60 to 75 minutes, laying a loose sheet of foil over the top at about 40 minutes to stop it over-browning. A toothpick in the center should come out with a few moist crumbs but no wet batter, and an instant-read thermometer should read 205F to 210F.
Cool a loaf in the pan for 10 minutes, then turn out onto a wire rack and cool completely before slicing. Muffins can come out of the tin after 5 minutes.
Notes
Muffins or loaf: The same batter does both. Muffins are the more reliable format, since they bake through in half an hour with no risk of a wet center, and they freeze better. One batch makes about 18.Measure the banana, do not count it: At 450 g of banana against 240 g of flour, the fruit outweighs the flour nearly two to one, and banana size varies enormously. Mash into a measuring cup or weigh it and stop at 2 cups or 450 g, roughly 4 to 5 medium bananas. Slightly short is fine and bakes faster; well over is where a wet center comes from.Banana ripeness: Use fruit that is at least half black and smells sweet. Whole wheat is an assertive flour and will bury the flavor of underripe bananas entirely. To ripen quickly, bake them unpeeled at 300F for 15 to 20 minutes until the skins are glossy black, then cool and mash.Whole wheat notes: Regular whole wheat gives the nuttiest loaf. White whole wheat swaps in one for one for a milder, paler result that is still 100 percent whole grain. For something between this and a classic loaf, use 1 cup whole wheat and 1 cup all-purpose. Whole wheat absorbs liquid as it sits, so the batter thickening after mixing is normal and needs no correction.Dairy free: The recipe is dairy free as written. Olive oil replaces butter and there is no milk in the batter.Foil the loaf: Whole wheat bran and brown sugar both darken quickly, so a loose foil tent from about 40 minutes is what keeps the crust from burning during a 60 to 75 minute bake. Muffins do not need it.Do not let the batter sit: The baking soda begins reacting with the acid in the discard and bananas as soon as they meet, and that reaction does not restart in the oven. Heat the oven and prepare the pans before you start mixing.Add-ins: Fold in 1 cup blueberries (frozen, unthawed, plus 3 to 5 minutes bake time), or 3/4 cup toasted walnuts, pecans, or semisweet chocolate chips.Storage: Wrapped tightly at room temperature, the loaf or muffins keep 3 to 4 days. The olive oil and whole wheat both help it stay soft. Do not refrigerate. To freeze, cool completely, freeze muffins in a single layer then bag them, or wrap a loaf whole or in slices. Both keep 3 months.