Sourdough Banana Crumble Muffins

If you think banana muffins are just a vehicle for using up overripe fruit, allow me to ruin basic banana muffins for you forever. These Sourdough Banana Crumble Muffins aren’t just a step up—they’re a whole category upgrade. With a rich, tender crumb thanks to the unexpected addition of sourdough starter (yes, even the flat stuff hiding in your fridge), and a buttery brown sugar streusel that melts into every bite, they balance breakfast and dessert without apology.

And for the gluten-conscious bakers among us—there’s an optional overnight fermentation step that makes them even more luxurious while fermenting the grains to make them extra easy on the tummy.

Why Use Sourdough in Muffins?

Using sourdough discard in muffins adds a slight tang, enhances moisture retention, and makes the crumb softer and more tender. The fermentation process also helps break down gluten, making these muffins easier to digest.

Do I have to long-ferment these Muffins?

No! You can mix up this batter if you want muffins quickly. Directions will be listed below.

As an amazon affiliate, this post may contain affiliate links. Which means I may receive a commission for qualifying purchases. I will only recommend products that I personally love and use.

Tools You’ll Need:

• Standard 12-cup muffin tin- for baking muffins. I love these pans from Wilton linked here https://amzn.to/3FYfXo1

• Muffin liners or nonstick spray- to avoid burned edges

• Kitchen scale (optional)– for accurate measuring—especially helpful with sourdough baking

• Masher– for mashing bananas

• Whisk + spatula- for combining ingredients

•  Mixing bowls- for mixing batter and crumble

• Hand mixer or sturdy whisk- for mixing batter

• Cooling rack– to cool muffins

Gather Your Ingredients:

Bananas– Brings natural sweetness, moisture, and structure to the muffin base. I like to use bananas that are extra ripe for added sweetness. You can even use frozen if you allow them to thaw completely-drain- and then mash!

Avocado oil- Neutral flavor and a tender crumb without greasiness. You can substitute another neutral oil if needed.

Sour cream– Adds moisture and tang to balance sweetness and enhance richness.

Brown sugar– Provides caramel depth and chew.

White sugar– Boosts sweetness and supports the rise and golden color.

Vanilla extract- Enhances the banana flavor and brings warmth.

Sourdough starter-(flat or past peak, can be cold or room temperature) Adds depth of flavor, moisture, and just a whisper of tang—without making this a “sour” muffin. Key for fermentation.

Eggs (room temperature)– provide structure and lift with moisture, works as a binder for ingredients.

All-purpose flour- Gives the muffins structure while keeping them soft and cakey.

Baking powder + Baking soda– Ensures the right rise and tenderness.

Salt- Balances sweetness and enhances all the other flavors.

Cinnamon, Ginger, Nutmeg, and Cardamom- These spices round out the banana flavor with cozy, aromatic warmth.

Chopped walnuts or pecans (Optional)- Adds texture and a nutty complement to the banana and streusel.

Unsalted butter– Brings streusel together and helps it crisp up in the oven.

Now let’s bake banana muffins!

Sourdough Banana Crumble Muffins

Wet Ingredients:

• 4 medium ripe bananas, mashed (350g or 1⅓ cups)

• ½ cup avocado oil (115g)

• ⅓ cup sour cream (70g)

• ½ cup brown sugar, packed (100g)

• ½ cup white sugar (100g)

• 2 tsp vanilla extract (8g)

• ½ cup sourdough starter, flat or past peak (120g)

• 2 large eggs (brought to room temperature)

Dry Ingredients:

• 2½ cups all-purpose flour (300g)

• 2 tsp baking powder

• 1 tsp salt

• ½ tsp baking soda

• 2 tsp ground cinnamon

• ½ tsp ground ginger

• ¼ tsp ground nutmeg

• ⅛ tsp ground cardamom

Optional Mix-Ins:

• ¾ cup chopped walnuts or pecans (100g)

Instructions

Mash your bananas and set aside. In a separate bowl, add the avocado oil, sour cream, eggs, brown sugar, white sugar, vanilla, and sourdough starter. Beat until smooth with hand beaters or a sturdy whisk. Add bananas to batter and beat in for 30 seconds.

In a clean bowl, sift together flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and cardamom. Add to wet ingredients and beat until just combined.

Overnight Ferment Option: if you want to ferment your batter overnight, cover with plastic at this point and transfer to the refrigerator for 12-18 hours. Don’t add nuts until the next morning. Otherwise, skip this step and proceed with the recipe for same day baking.

Next, fold in your nuts if desired into batter. Set batter aside and mix your streusel.

Cinnamon Brown Sugar Crumble

In a medium bowl, whisk together:

• ¾ cup (90g) all-purpose flour

• ¼ cup (50g) granulated sugar

• ½ cup + 1 tbsp (95g) brown sugar

• 1½ tsp (4g) ground cinnamon

• Pinch of salt

Add in:

2 tbsp (30g) sourdough discard

3 tbsp (43g) softened unsalted butter

Mix with a fork or your fingers until crumbly.

Bake Your Muffins:

If batter was in refrigerator overnight, remove and allow to warm up while oven is preheating.

Preheat oven to 425°F (218°C). Line muffin tin with parchment liners. Scoop ⅓ cup batter into each well, filling nearly to the top. Add a heaping spoonful of crumble topping to each.

Bake at 425°F for 6 minutes, then reduce temperature to 350°F (177°C) and bake an additional 20–22 minutes, or until a toothpick comes out clean.

Let muffins cool in the pan for 5 minutes, then transfer to a wire rack.

Enjoy your muffins with a little butter!

Whether you’re chasing down that perfect bakery-style banana muffin or just want to use up those bananas on the counter and that discard in the fridge, these Sourdough Banana Crumble Muffins are the kind of recipe you’ll want to print and tape to the fridge.

Moist, spiced, and unapologetically indulgent—this is the muffin that doesn’t pretend to be anything less than dessert, but you can feel good eating it!

Go ahead and make the batter tonight. Bake them tomorrow. But don’t be surprised when these Sourdough Banana Crumble Muffins become your new not-so-guilty pleasure.