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These Sourdough Pumpkin Spice Bars are the ultimate cozy fall dessert! Made with real pumpkin purée, warm spices, and tangy sourdough starter, they’re soft, moist, and perfectly balanced with creamy homemade cream cheese frosting. This easy one-bowl recipe is the best way to use up sourdough discard and bring the flavors of fall to your table.

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Why You’ll Love These Sourdough Pumpkin Spice Bars

• They’re soft, moist, and full of cozy fall flavor.

• The sourdough starter adds a subtle tang that balances the sweetness.

• Quick and easy — mix everything in one bowl, no kneading or proofing.

• Perfect for fall gatherings, Thanksgiving, or afternoon tea.

• Freezer-friendly and great for make-ahead desserts!

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Tools you may need

• Kitchen aid stand mixer
• 9×13 baking pan
• Mixing cups and spoons

Ingredients

Cake:

• Eggs: Eggs act as a binding agent and provide structure to the bars. They contribute to the overall texture and help with leavening.
• Sugar: Sugar adds sweetness to the bars. It also helps in creating a tender texture and contributes to browning during baking.
• Oil: Oil adds moisture to the bars, making them soft and moist. It also enhances the overall richness of the bars. You can use any oil like avocado, olive, or coconut oil.
• Pumpkin Puree: Pumpkin puree is the key ingredient that gives these bars their pumpkin flavor and moist texture. It also adds natural sweetness.
• Sourdough Starter: Sourdough starter adds a tangy and slightly fermented flavor to the bars. You can use fed or unfed sourdough starter.
• Flour: Flour is the main dry ingredient that provides structure to the bars. It forms the base of the batter. I recommend King Arthur All Purpose Flour or Bread Flour.
• Baking Powder: Baking powder is a leavening agent that helps the bars rise and become light and fluffy. I recommend Bob’s Red Mill Baking Powder.
• Cinnamon: Cinnamon adds a warm and aromatic spice flavor to the bars, complementing the pumpkin.
• Salt: Salt enhances the overall flavor of the bars. It also balances the sweetness and other flavors in the recipe.
• Baking Soda: Baking soda is another leavening agent that interacts with the acid in the sourdough starter to help the bars rise.
• Nutmeg (optional): Nutmeg adds a warm and nutty flavor to the bars. It’s optional but can enhance the overall spice profile.

Cream Cheese Frosting:

• Cream cheese:  Softened cream cheese is perfect for frosting
• Powdered sugar: Mixed with the cream cheese to create a sweet, tangy frosting.

Step-by-Step Instructions for Sourdough Pumpkin Bars

1. Mix Starter with Baking Soda

1. In a small bowl, combine the sourdough starter with baking soda.

2. The starter’s natural acidity reacts with the soda, giving your bars a light, fluffy texture.

2. Prepare the Batter

1. In a large bowl or stand mixer, whisk together eggs, sugar, oil, and pumpkin purée until smooth.

2. Add the starter + baking soda mixture and mix well.

3. Stir in baking powder, salt, cinnamon, and nutmeg (if using).

4. Gradually fold in all-purpose flour until fully combined and smooth.

3. Bake the Pumpkin Spice Bars

1. Preheat oven to 175 °C (350 °F).

2. Grease or line a 23×33 cm (9×13 inch) baking pan.

3. Pour in the batter and bake for 40–50 minutes, until a toothpick inserted in the center comes out clean.

4. Allow the bars to cool completely before frosting.

4. Make Cream Cheese Frosting

1. Beat cream cheese in a stand mixer for 3–5 minutes until fluffy.

2. Gradually add powdered sugar and mix until smooth and creamy.

5. Frost and Serve

Spread frosting evenly over the cooled pumpkin bars. Slice and enjoy your moist and flavorful sourdough pumpkin bars!

Tips for the Best Pumpkin Bars

• Use active or discard sourdough starter — both work!

• Don’t overmix once you add the flour; it keeps the bars soft.

• Make sure the cake is fully cooled before adding frosting.

• For a lighter texture, fold in a bit of Greek yogurt or applesauce.

• Want to make it extra special? Add chopped pecans or white chocolate chips.

Storage and Freezing

• • Store: Keep leftovers in an airtight container in the fridge for up to 5 days.

  • Freeze: Wrap individual bars tightly and freeze for up to 2 months. Thaw overnight in the fridge.

  • Pro Tip: Frost just before serving if freezing for the best texture.

Variations

• Gluten-free: Use a 1:1 gluten-free flour blend.

• Dairy-free: Swap cream cheese for vegan cream cheese and use coconut oil in the batter.

• Maple version: Replace part of the sugar with maple syrup for a deeper flavor.

Frequently Asked Questions

Can I use unfed sourdough starter?
Yes! Both fed and unfed starter work — unfed gives a slightly tangier flavor.

Can I make these bars ahead of time?
Absolutely. Bake a day ahead and frost before serving. They taste even better the next day!

Can I double the recipe?
Yes, you can bake it in a larger sheet pan for a crowd. This recipe makes a 9×13 pan cake, and it rises quite a bit.

Sourdough Pumpkin Spice Bars

These sourdough pumpkin spice bars offer a unique twist on the traditional pumpkin spice treats, with the tangy notes of sourdough and warm pumpkin spice is a delight in every bite.

5 from 2 votes

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 40 minutes mins

Course Dessert

Cuisine American

Servings 4 people

Calories 10 kcal

Ingredients

  

For the Cake:

• 3 large eggs 150 g
• 300 g sugar
• 100 g oil any neutral oil — avocado, olive, or coconut
• 450 g pumpkin purée about 1 full 15 oz can
• 120 g sourdough starter fed or unfed
• 250 g all-purpose flour or bread flour
• 2 tsp baking powder
• 2 tsp cinnamon
• 1 tsp salt
• 1 tsp baking soda
• ½ tsp nutmeg optional, for extra warmth

For the Cream Cheese Frosting:

• 225 g cream cheese softened (1 package)
• 240 g powdered sugar 2 cups

Instructions

 

Make the Batter:

• In a small bowl, mix the sourdough starter with baking soda and let it bubble for about 1 minute. This helps activate the rise and gives a light, fluffy texture.
  120 g sourdough starter, 1 tsp baking soda
• In the bowl of a stand mixer, whisk together the eggs, sugar, oil, and pumpkin purée until smooth.
  3 large eggs, 300 g sugar, 100 g oil, 450 g pumpkin purée
• Add the starter–baking soda mixture to the bowl and mix briefly to combine.
• Add the baking powder, salt, cinnamon, and nutmeg, and mix on low speed.
  2 tsp baking powder, 2 tsp cinnamon, 1 tsp salt, ½ tsp nutmeg
• Gently mix in the flour until just combined — don’t overmix to keep the crumb soft.
  250 g all-purpose flour

Bake the Bars:

• Preheat oven to 350°F (175°C).
• Grease or line a 9×13-inch (23×33 cm) baking pan.
• Pour the batter into the pan and spread evenly.
• Bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean.
• Let the cake cool completely before frosting.

Prepare the Frosting:

• In a stand mixer, beat cream cheese for 3–5 minutes until light and creamy.
  225 g cream cheese, 240 g powdered sugar
• Add powdered sugar and beat again until smooth and fluffy.
• Spread evenly over cooled bars.

Serve and Enjoy:

• Cut into squares or rectangles and enjoy these soft, spiced, tangy-sweet sourdough pumpkin bars with tea or coffee. Perfect for cozy fall days or your Thanksgiving dessert table!

Notes

Storage:
Fridge: Store covered up to 5 days.
Freezer: Freeze unfrosted bars up to 2 months. Thaw overnight and frost before serving.

Keyword pumpkin spice bars, sourdough

If you tried this recipe and love it, please come back and give it a review or a comment. Tag me on IG @shakanranch