Easy Sourdough Discard Banana Bars Recipe

Incredibly light and moist banana cake with a delicious vanilla glaze. This sourdough banana bars recipe is a no-wait recipe that is sure to be a crowd favorite. Prepared with common household ingredients, makes this recipe a go-to sweet treat.

One of the first desserts my husband ever baked for me was a family favorite of his – banana bars. I grew up eating plenty of homemade banana bread but had never had banana bars before. After one bite, they quickly became a new favorite of mine.

If you have never had the pleasure of enjoying banana bars, they are a banana lover’s dream! The crumb is super tender, but still just as moist as your classic banana bread, and has a light, but delicious banana flavor. Then, to take them one step further, they are topped off with a thick layer of sweet vanilla glaze.

As you might know, I am a huge sourdough fan! From sourdough bread to homemade sourdough bagels, I can’t get enough! So I just had to put a few little tweaks to this easy recipe to make it sourdough!

Sourdough starter discard is a wonderful addition to recipes like cheddar and chive savory sourdough Irish soda bread or these sourdough banana bars because of its naturally acidic qualities. Just like the sour cream, the unfed sourdough starter will react with the baking soda to help the bars rise and create a light crumb. So light in fact that eating one sourdough banana bar will simply never be enough.

Now, whenever overripe bananas have overstayed their welcome and there is an excess of sourdough starter in my fridge, sourdough banana bars are one of my family’s favorite sourdough discard recipes.

MY LATEST VIDEOS

Pin for Later:

As an Amazon Associate, I earn from qualifying purchases. This post may contain affiliate links, which means I make a small commission at no extra cost to you. See my full disclosure here.

Why You’ll Love This Recipe:

• Making sourdough banana bars is the perfect way to use overripe bananas while also eliminating food waste. Never throw away another banana again!
• Another item you’ll never need to toss is sourdough starter discard. Excess sourdough starter gives these sourdough banana bars a delicious flavor, plus some fermentation for gut health.
• Sourdough recipes are known for their unique tangy flavor. Sourdough banana bars have a perfect balance of sourdough flavor and sweetness.

Ingredients:

Flour: I used all-purpose flour for this recipe. King Arthur’s All-Purpose Flour is an excellent choice!

White Sugar

Eggs

Sour cream: Sour cream reacts with baking soda to help the sourdough banana bars rise, while keeping the bars extra moist.

Mashed banana: Brown bananas are the perfect sweetness for these banana bars. In fact, the riper the better! You can also use frozen brown bananas in this recipe. Just thaw them until soft enough to mash.

Vanilla: Pure vanilla extract would be preferred for this recipe, but use what you have!

Baking soda: If your baking soda may have been hiding in the back of your pantry, make sure it hasn’t expired. Using expired baking soda will cause the banana bars to be dense and chewy.

Sourdough starter: Leftover discard works best for this delicious treat.

Butter: Softened

Salt: Any salt will do, but I prefer to use Redmond’s Unrefined Fine Salt for the extra minerals

For the vanilla glaze:

Powdered sugar

Butter: Softened

Vanilla

Warm water

Supplies:

Stand mixer or hand mixer

Small bowl

Kitchen scale

Measuring cups and spoons

Rimmed baking sheet – I use this Nordic Ware and it is perfect for this recipe.

Wire rack

How to Make Sourdough Banana Bars:

Preheat oven to 375 degrees.

Add sugar, sour cream, butter, and eggs to a stand mixer with the paddle attachment. Mix on low speed for about 1 minute. Scrape the sides of the bowl occasionally.

Beat in mashed bananas, sourdough starter, and vanilla on low for 30 seconds.

Add the flour, baking soda, and salt in a separate bowl. Mix well with a fork.

Add the dry ingredients to the wet ingredients in small batches and beat on medium speed for 1 minute. You don’t want flour flying everywhere…speaking from experience. Scrape the sides occasionally.

Pour the batter into a greased, rimmed baking sheet, like the Nordic Ware I use. I like to use butter, but nonstick spray would work as well.

Place the baking sheet in the preheated oven on the middle rack. Bake for 20-25 minutes, or until golden brown.

Cool on a wire rack.

How to Make Vanilla Glaze:

While the banana cake is on the cooling rack, it is time to prepare the vanilla glaze.

In a medium bowl, mix powdered sugar, softened butter, vanilla, and hot water with a hand mixer. Continue to add additional hot water (1-2tsp) until the glaze is smooth and at desired consistency.

I like to spread the glaze on the banana bars while the cake is still a bit warm. The glaze will melt just a bit and it is easier to spread.

It’s almost like a “Goldy Locks” situation. If you spread the glaze on when the banana bars are too hot, the glaze will completely melt. But, if you spread the glaze on when the banana bars are completely cool, the glaze will stick to the bars and be a pain to spread.

I find it “just right” when the sourdough banana bars are just warm to the touch. Or if you are like my husband, then the perfect solution is to simply make a double batch of the vanilla glaze so that each sourdough bananas bars is covered perfectly.

How to Serve Sourdough Banana Bars:

Sourdough banana bars are perfectly delicious when they are served on their own. But don’t get me wrong, adding a scoop of vanilla ice cream or a dollop of homemade whipped cream wouldn’t hurt anything!

If you are a fan of homemade banana bread with walnuts, sprinkle chopped walnuts on top of your sourdough banana bars for an extra crunch!

How to Store Sourdough Banana Bars:

Store leftover banana bars at room temperature in an airtight container or covered with plastic wrap. They will keep for 3-4 days.

Do not put them in the fridge, though. The cool, circulating air will remove moisture from your banana bars, causing them to dry out prematurely. No one wants a dry sourdough banana bar!

FAQs:

Can You Freeze Sourdough Banana Bars?

You can absolutely freeze the banana bars! Cover the crumb as a whole with multiple layers of plastic wrap after it has thoroughly cooled. They will keep in the freezer for up to 3 months.

When you are ready to serve, remove the banana bars from the freezer and allow them to thaw back to room temperature before spreading on the vanilla glaze.

Can You Use Green Bananas?

Unfortunately, no. The browner and riper the bananas are, the sweeter your banana bars will be! Most of the time I will let my banana sit out as long as possible before they attract any fruit flies. Then I’ll pop them in the freezer until I am ready to bake. That way I always have bananas on hand to make sourdough banana bars.

Happy baking!

Other Sourdough Recipes:

Sourdough Discard Pie Crust

Easy Sourdough Bread for Beginners

Homemade Sourdough Bagels

FULL RECIPE TUTORIAL