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Best Sourdough Zucchini Bread in a Loaf Pan

Best Sourdough Zucchini Bread

  • Author: Emilie Raffa
  • Yield: 1 loaf
  • Category: Sourdough Discard Recipes
  • Method: Baking
  • Cuisine: American
  • Diet: Vegetarian


This is my recipe for the best zucchini bread (ever!) using leftover sourdough starter discard. The secret is a specific mixing order- you’ll get the most amazing, melt-in-your-mouth texture every time!

Notes & Substitutions

  • Non-Sourdough Version: Just leave it out. No additional adjustments needed.
  • Dairy Free: Use unsweetened almond milk or another plant milk of your choice. Use oil or plant butter to coat the pans.
  • Gluten Free: Use King Arthur Measure for Measure Flour & a GF sourdough starter
  • Pan Sizes: (2 or 3) mini 7 x 3 x 2- inch OR (1) standard 9 x 5-inch


  • Butter, for coating the pan
  • 2 cups (220 g) grated zucchini, from appx. 1 medium zucchini
  • 125 g banana weighed with the skin on (about 1 small banana) 
  • 225 g (1 1/4 cups lightly packed) light or dark brown sugar
  • 1½ tsp pure vanilla extract
  • 2 large eggs
  • 100 g (appx. 1/2 cup) sourdough discard OR bubbly, active 100% hydration starter
  • 250g (2 cups) all-purpose flour
  • 1 tsp cinnamon
  • 1/8 tsp nutmeg
  • 1½ tsp baking soda
  • 1/4 tsp fine sea salt
  • 125 ml (½ cup) neutral flavored oil like sunflower (mild olive oil works, too)
  • 60 ml (1/4 cup) milk or unsweetened almond milk


How to Prepare your Sourdough Starter: if using leftover sourdough discard, make sure it’s in good condition (no brown liquid, no vinegary smell, not straight from the fridge). I use recently fed or just collapsed starter. Alternatively, if using active starter, you’ll need to feed it prior to making the recipe and wait for it to become bubbly and double in size.

  1. Preheat the oven to 360 F. Lightly coat (2 or 3) 7 x 3 x 2 mini loaf pans or (1) 9 x 5-inch loaf pan with butter. Note: Using 2 mini loaf pans instead of 3 will you get you slightly taller loaves.
  2. Using a box grater, grate the zucchini on an angle on the side with largest holes. No need to drain out the excess water. Set aside.
  3. Add the banana, sugar, and vanilla to a large mixing bowl. Cream with a hand held mixer or stand mixer fitted with the paddle attachment, about 30 seconds to 1 minute (some small lumps of banana are okay).
  4. Add the eggs, one at a time until fully incorporated. Add the sourdough starter.
  5. Sift the flour, cinnamon, nutmeg, baking soda, and salt together in a separate bowl. Working in batches, add this to the banana mixture.
  6. Add the oil and milk and mix until just combined. Do not over do it; the banana bread will be tough. The texture should be thick and pourable, but not runny. Add more flour if needed. Fold in the grated zucchini.
  7. Pour the batter into the prepared pan(s). For 2 mini loaf pans, fill about 3/4’s full. For 3 mini loaf pans, fill about 2/3’s full (these loaves will not be as high). Place onto a baking sheet and transfer to the oven.
  8. Bake for 40-45 minutes for the 2 mini loaf pans (about 30-35 minutes if using 3 mini pans) or 60-65 minutes or more for the standard 9 x 5-inch pan. Cover with foil if the loaf browns too quickly.
  9. Cool in the pan for 20 minutes, and then transfer to a wire rack to cool completely.


  • To Store: wrap the loaves (plastic or reusable wrap) and keep at room temperature. Because of the moisture in the zucchini, the texture will get softer and softer each day.
  • To Freeze: Once completely cool, wrap the loaves, label and date; they will keep for up to 3 months. Defrost at room temperature.
  • To Double: simply double the ingredients as listed. I recommend using a stand mixer.

Keywords: sourdough zucchini bread, best, easy recipe, moist zucchini bread, sourdough discard, sourdough starter, zucchini recipes, quick bread recipes