Sourdough Zucchini Bread (with cinnamon sugar topping)

Summer just doesn’t feel like summer without a loaf of zucchini bread on the counter. Every year, as soon as the zucchini starts piling up, this is the recipe I make first. This Sourdough Zucchini Bread (with cinnamon sugar topping) is soft, perfectly spiced, topped with a sweet cinnamon sugar crust, and somehow tastes even better the next day. If you’re looking for the perfect way to use up fresh summer zucchini, this is it!
Pair this bread with my Honey Cinnamon Butter for the perfect summer breakfast or snack!
Why You’ll Love This Recipe
- Incredibly moist: The addition of zucchini to this bread soft, tender, and delicious for days.
- Perfect for summer zucchini: Whether it’s from your garden, a neighbor, or the farmer’s market, this recipe is the best way to use it up.
- Cinnamon sugar topping: A generous sprinkle of cinnamon sugar creates a sweet crust on every loaf.
- Easy to make: This recipe uses simple pantry staples making it a recipe you’ll come back to every zucchini season.
- Uses up discard: Have sourdough discard to use? This is a delicious option!
Tools You’ll Need:
- Cheese or veggie grater- for grating the zucchini. You can also use your food processor with your grating attachment if you prefer.
- Whisk- for mixing the batter.
- Mixing bowl– to mix wet and dry ingredients. I love these mixing bowls linked here that have lids for easy refrigerator fermentation.
- Kitchen scale (optional)– for accurate measuring, especially helpful with sourdough baking linked here.
- Measuring cups and spoons- if not using a scale and for smaller ingredients.
- Spatula– to fold ingredients.
- 9×5-inch loaf pan- to bake your loaf. Make sure you use a true 9×5 or you may have spillage, or don’t add all of the batter to the pan. This USA pan linked here is my favorite for baking.
- Parchment paper– to line your pan to avoid burning. This is very important!
- Small metal clips (optional)- to clip the parchment to the pan linked here.

Gather Your Ingredients:
- Fresh Zucchini– Brings natural sweetness, moisture, and tenderness to the bread. It’s the secret to that soft texture that stays fresh for days.
- Avocado Oil- keeps the bread soft. You can substitute for any neutral cooking oil.
- Sour cream– Adds moisture and richness to the bread and locks in moisture.
- Brown sugar– Sweetens and adds molasses flavor to the bread.
- White sugar– Sprinkled on top in the cinnamon sugar.
- Vanilla extract- Enhances and balances flavors.
- Sourdough starter- (flat or past peak, can be cold or room temperature). Adds depth of flavor and moisture without making this loaf “sour”. Key for fermentation.
- Eggs + egg yolk (room temperature)– provide structure and lift to the bread.
- All-purpose flour- Gives the bread structure while keeping it soft and cakey.
- Baking powder + Baking soda– Ensures the right rise and tenderness.
- Sea Salt- Balances sweetness and enhances all the other flavors.
- Cinnamon, Ginger, Nutmeg and Cardamom- These spices round out the zucchini flavor and bring cozy warmth.
- Chopped walnuts or pecans (optional)- Adds texture and crunch to the bread.

Instructions
Step 1: Mix the Batter
Wash and cut the ends off of the zucchini. Shred the zucchini with a cheese grater or a food processor using the grating attachment. Once the zucchini is shredded, transfer to a bowl and set aside for later.
Please note if you’re fermenting this batter overnight you can shred the zucchini the next day as you will add it then.
In a small bowl, combine the sugar and cinnamon for the topping and set aside.
Whisk together the oil, sour cream, sourdough discard, brown sugar, eggs, egg yolk, and vanilla until smooth in a mixing bowl.
In a separate bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and cardamom until all of the ingredients are combined.
Add the dry ingredients to the wet ingredients, and gently whisk the batter until no streaks of flour remain. Be careful not to overmix the batter at this stage or the crumb will be tough.
Add the shredded zucchini to the batter and fold into the batter until just incorporated. Avoid overmixing.


Overnight ferment option: To ferment this batter, don’t add the shredded zucchini to the bread yet or the bread will be gummy. Cover the batter after adding the dry ingredients and transfer to the refrigerator overnight for optional fermentation.
Step 2: Bake the Zucchini Bread
Continued overnight fermentation: If your batter was refrigerated overnight, remove it from the refrigerator and allow it to rest at room temperature for about 1 hour until the batter is roughly 70 degrees. Add the shredded zucchini and fold in before baking.
Preheat the oven to 375°F. Grease and line a 9×5-inch loaf pan with parchment paper. Don’t skip lining the pan with parchment, it will help make removing the loaf easy. I like to use little metal clips to clip the parchment while I pour the batter.
Pour the batter into the prepared pan, smooth the top, and sprinkle the top with the cinnamon sugar blend.
Batter should only fill the pan 2/3 of the way full, more than this could lead to spillage. I like to place a cookie sheet on the rack beneath my bread to avoid any messy ovens.

Transfer the loaf to the hot oven and bake at 375°F for 10 minutes, then without opening the oven drop the temperature to 350°F and bake an additional 50-60 minutes. The center should feel firm and a toothpick should have a few moist crumbs when the loaf is done. Loaf internal temperature should be 195 F.
These baking times are a guide, please follow the additional visual cues to make sure the loaf is done before removing from heat. If the top starts to brown, tent the top with foil and continue baking.
The internal temperature of the bread should be 200-205 F when done. Cool in the pan 10 minutes, then transfer to a cooling rack. Allow to cool 30 minutes before slicing.
Yields 1 loaf

How to store:
Room temperature- Store loaf in an airtight container or wrapped in plastic at room temperature for 3 days.
Refrigerator- Store in refrigerator in airtight container or wrapped in plastic for up to 7 days.
Freezer- Wrap loaf in plastic and then wrap in foil to avoid freezer burn. Freeze for up to 3 months. When ready to enjoy loaf, allow to thaw at room temperature overnight. Serve!
FAQ’S
Absolutely! just bake right after mixing in the zucchini for a delicious quick version.
Yes! Flat, unfed starter is perfect for this recipe.
Yes, full-fat Greek yogurt will work.
It was either underbaked or overmixed. Let it bake fully and cool slowly for the best texture.
If you loved this recipe, drop a comment and leave a star review and don’t forget to checkout more of my sourdough quick bread recipes!
Sourdough Quick Bread Recipes:
- Sourdough Lemon Loaf (Starbucks Copycat)
- Sourdough Brown Butter Banana Bread
- Sourdough Chocolate Zucchini Bread
- Sourdough Strawberry Quick Bread

Sourdough Zucchini Bread (with cinnamon sugar topping)
Equipment
- Cheese or veggie grater – for grating the zucchini. You can also use your food processor with your grating attachment if you prefer. I like this veggie grater.
- Whisk – for mixing the batter.
- Mixing Bowl – to mix wet and dry ingredients. I love these mixing bowls linked here that have lids for easy refrigerator fermentation.
- Kitchen scale (optional) – for accurate measuring, especially helpful with sourdough baking linked here.
- Measuring cups and spoons – if not using a scale and for smaller ingredients.
- Spatula – to fold ingredients.
- 9×5-inch loaf pan – to bake your loaf. Make sure you use a true 9×5 or you may have spillage, or don't add all of the batter to the pan. This USA pan linked here is my favorite for baking.
- Parchment paper – to line your pan to avoid burning. This is very important!
- Small metal clips (optional) – to clip the parchment to the pan linked here.
Ingredients
Wet Ingredients:
- 2 (260g) cups zucchini shredded
- 1/2 (120g) cup avocado oil or vegetable oil
- 1/4 (60g) cup sour cream
- 1/2 (120g) cup sourdough discard
- 1 1/4 (265g) cups brown sugar
- 2 eggs
- 1 egg yolk
- 2 tsp vanilla extract
Dry Ingredients:
- 2 1/4 (275g) cups all-purpose flour
- 3/4 tsp baking soda
- 1 1/2 tsp baking powder
- 1 tsp fine sea salt
- 1 1/2 tsp ground cinnamon
- 1/4 tsp ground nutmeg
- 1/4 tsp ground ginger
- 1/8 tsp ground cardamom
Cinnamon Sugar Topping:
- 2 (25g) Tbsp granulated white sugar
- 1/2 tsp ground cinnamon
Mix-in's:
- 1/2 (60g) cup walnuts or pecans chopped
Instructions
Step 1: Mix the Batter
- Wash and cut the ends off of the zucchini. Shred the zucchini with a cheese grater or a food processor using the grating attachment. Once the zucchini is shredded, transfer to a bowl and set aside for later.2 (260g) cups zucchini
- Please note if you’re fermenting this batter overnight you can shred the zucchini the next day as you will add it then.
- In a small bowl, combine the sugar and cinnamon for the topping and set aside.2 (25g) Tbsp granulated white sugar, 1/2 tsp ground cinnamon
- Whisk together the oil, sour cream, sourdough discard, brown sugar, eggs, egg yolk, and vanilla until smooth in a mixing bowl.1/2 (120g) cup avocado oil, 1/4 (60g) cup sour cream, 1/2 (120g) cup sourdough discard, 1 1/4 (265g) cups brown sugar, 2 eggs, 1 egg yolk, 2 tsp vanilla extract
- In a separate bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and cardamom until all of the ingredients are combined.2 1/4 (275g) cups all-purpose flour, 3/4 tsp baking soda, 1 1/2 tsp baking powder, 1 tsp fine sea salt, 1 1/2 tsp ground cinnamon, 1/4 tsp ground nutmeg, 1/8 tsp ground cardamom, 1/4 tsp ground ginger
- Add the dry ingredients to the wet ingredients, and gently whisk the batter until no streaks of flour remain. Be careful not to overmix the batter at this stage or the crumb will be tough.
- Add the shredded zucchini to the batter and fold into the batter until just incorporated. Avoid overmixing.
- Overnight ferment option: To ferment this batter, don't add the shredded zucchini to the bread yet or the bread will be gummy. Cover the batter after adding the dry ingredients and transfer to the refrigerator overnight for optional fermentation.
Step 2: Bake the Zucchini Bread
- Continued overnight fermentation: If your batter was refrigerated overnight, remove it from the refrigerator and allow it to rest at room temperature for about 1 hour until the batter is roughly 70 degrees. Add the shredded zucchini and fold in before baking.
- Preheat the oven to 375°F. Grease and line a 9×5-inch loaf pan with parchment paper. Don’t skip lining the pan with parchment, it will help make removing the loaf easy. I like to use little metal clips to clip the parchment while I pour the batter.
- Pour the batter into the prepared pan, smooth the top, and sprinkle the top with the cinnamon sugar blend.
- Batter should only fill the pan 2/3 of the way full, more than this could lead to spillage. I like to place a cookie sheet on the rack beneath my bread to avoid any messy ovens.
- Transfer the loaf to the hot oven and bake at 375°F for 10 minutes, then without opening the oven drop the temperature to 350°F and bake an additional 50-60 minutes. The center should feel firm and a toothpick should have a few moist crumbs when the loaf is done. Loaf internal temperature should be 195 F.
- These baking times are a guide, please follow the additional visual cues to make sure the loaf is done before removing from heat. If the top starts to brown, tent the top with foil and continue baking.
- The internal temperature of the bread should be 200-205 F when done. Cool in the pan 10 minutes, then transfer to a cooling rack. Allow to cool 30 minutes before slicing.
- Pair with my Honey Cinnamon Butter!
- Yields 1 loaf

Love this recipe! The subtle flavor of the cardamom is next level good. The bread is moist and delicious! I love the depth of flavor from the addition of browned butter. Will definitely make this again!
I’m so glad that this recipe was a success and well loved! Thank you for your comment!
I’m so glad you enjoyed this! Thank you for your review!
Oh man! Thats a keeper recipe for sure!!! So delish! My house smells amazing too. I skipped the overnight ferment and went for it. AMAZING!
Hi Cara, that cinnamon sugar really makes the whole house smell wonderful. Thank you for your review!