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–+ servings
Sourdough banana bars with vanilla glaze and walnut topping

Sourdough Banana Bars Recipe

By McKenna Pulda
Yield: 30 bars
Prep Time: 15 minutes
Cook Time: 20 minutes
Total Time: 35 minutes
Incredibly light and moist banana cake with a sweet 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.
4.73 from 47 votes
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Equipment

Ingredients

Sourdough Banana Bars

  • 350 grams sugar 1 3/4 cups
  • 190 grams sour cream 3/4 cup
  • 113 grams unsalted butter, softened 1/2 cup
  • 100 grams eggs 2 large eggs
  • 380 grams mashed bananas, 1 1/2 cups , about 3 large bananas
  • 140 grams sourdough discard heaping 1/2 cup
  • 8 grams pure vanilla extract 2 teaspoons
  • 230 grams all-purpose flour 1 1/2 cups + 2 Tablespoons
  • 6 grams baking soda 1 teaspoon
  • 6 grams salt 1 teaspoon

Vanilla Glaze

  • 520 grams powdered sugar 4 cups
  • 113 grams unsalted butter, softened 1/2 cup
  • 12 grams vanilla extract 3 teaspoons
  • 56 grams warm water 4 Tablespoons

Instructions

  1. Preheat oven to 375 degrees F. Grease and line with parchment paper a rimmed 11 x 16 baking sheet. Set aside.
  2. Add sugar, sour cream, butter, and eggs to a stand mixer with the paddle attachment. Mix on low speed for about a minute. Scrape the sides of the bowl occasionally. There will be bits of solid butter in the mix and that is totally okay.
    You can also use a hand-mixer.
    350 grams sugar, 190 grams sour cream, 113 grams unsalted butter, softened, 100 grams eggs
  3. Beat in mashed bananas, sourdough starter, and vanilla on low for 30 seconds. It will be runny batter.
    380 grams mashed bananas, , 140 grams sourdough discard, 8 grams pure vanilla extract
  4. In a separate bowl, add the flour, baking soda, and salt. Mix well with a fork.
    230 grams all-purpose flour, 6 grams baking soda, 6 grams salt
  5. Add the dry ingredients to the wet ingredients in small batches and beat on medium speed for one minute. You don't want flour flying everywhere...speaking from experience.
  6. Occasionally scrape the sides of the bowl. The batter will be thicker, but still runny.
  7. Pour the batter into the prepared baking sheet and bake for 20-25 minutes, or until golden brown and a toothpick inserted in the center comes out clean.
  8. Cool on a wire rack for 5-10 minutes before topping with the vanilla glaze.

Vanilla Glaze

  1. 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 and it is easier to spread.
    520 grams powdered sugar, 113 grams unsalted butter, softened, 12 grams vanilla extract, 56 grams warm water
  2. Cut into squares and enjoy!

Notes

Recipe Tips

  • Store leftover banana bars at room temperature in an airtight container or covered with plastic wrap. They will keep for 3-4 days.
  • 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.
  • The more brown and ripe bananas you use, the sweeter the sourdough banana bars!
  • If you would like to bake a banana cake instead of banana bars, bake the batter in a greased 9x13 dish for 20-25 minutes.

Nutrition

Calories: 229kcal | Carbohydrates: 39g | Protein: 2g | Fat: 8g | Saturated Fat: 5g | Polyunsaturated Fat: 0.4g | Monounsaturated Fat: 2g | Trans Fat: 0.2g | Cholesterol: 32mg | Sodium: 141mg | Potassium: 69mg | Fiber: 1g | Sugar: 30g | Vitamin A: 254IU | Vitamin C: 1mg | Calcium: 12mg | Iron: 0.5mg
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