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Sourdough Banana Snack Cake with Brown Butter Cream Cheese Frosting on a plate.
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Sourdough Banana Snack Cake with Brown Butter Cream Cheese Frosting

This sourdough banana snack cake is soft, flavorful, and topped with a rich, nutty brown butter cream cheese frosting. It’s a great way to use up sourdough discard and overripe bananas — perfect for afternoon tea, lunchboxes, or a cozy dessert. With banana slices on top and a tangy-sweet frosting, it’s as beautiful as it is delicious.
Course Dessert
Cuisine American
Keyword brown butter frosting, snack cake, sourdough banana cake
Prep Time 25 minutes
Cook Time 35 minutes
Cooling Time 1 hour
Total Time 2 hours

Equipment

  • Mixing bowls
  • Hand mixer or stand mixer
  • Rubber spatula
  • 8x8-inch (20x20 cm) square baking pan
  • Saucepan (light-colored, for browning butter)
  • Sifter or fine mesh sieve
  • Parchment paper (optional)
  • Offset spatula or spoon (for frosting)

Ingredients

Banana Cake

  • 240  g ripe bananas mashed (about 2 medium)
  • 200  g granulated sugar
  • 115  g unsalted butter melted
  • 2 large eggs
  • 60  g sour cream or plain yogurt
  • 5  g vanilla extract 1 tsp
  • 2  g ground cinnamon ½–1 tsp, to taste
  • 2  g salt ¼ tsp
  • 120  g sourdough starter active or discard
  • 5  g baking soda 1 tsp
  • 190  g all-purpose flour
  • 3  g baking powder ¾ tsp
  • 1 ripe banana for topping, sliced into rings – optional

Brown Butter Cream Cheese Frosting

  • 115  g unsalted butter for browning
  • 225  g cream cheese softened
  • 180 –200 g powdered sugar
  • 5  g vanilla extract 1 tsp
  • Pinch of salt

Instructions

Brown the Butter (Start First)

  • In a small light-colored saucepan, melt 115 g unsalted butter over medium heat.
    115  g unsalted butter
  • Stir as it foams and bubbles. When it turns golden and smells nutty, remove from heat.
  • Pour into a heatproof bowl and let it cool completely (you can chill briefly, but don’t let it harden).

Prepare the Cake Batter

  • Preheat oven to 175°C (350°F). Grease or line an 8×8-inch baking pan with parchment paper.
  • In a large bowl, mash 240 g bananas until smooth.
    240  g ripe bananas
  • Add the following ingredients one at a time, mixing after each:
  • 200 g sugar
    200  g granulated sugar
  • 115 g melted butter
    115  g unsalted butter
  • 2 eggs
    2 large eggs
  • 60 g sour cream or yogurt, 5 g vanilla extract, 2 g cinnamon, and 2 g salt.
    60  g sour cream or plain yogurt, 5  g vanilla extract, 2  g ground cinnamon, 2  g salt
  • In a small bowl, mix 120 g sourdough starter with 5 g baking soda. Let sit for 1–2 minutes until bubbly, then stir into the batter.
    120  g sourdough starter, 5  g baking soda
  • Sift in 190 g flour and 3 g baking powder. Fold with a spatula just until no dry streaks remain.
    190  g all-purpose flour, 3  g baking powder
  • Pour batter into prepared pan and smooth the top. Add banana slices on top, if using.
    1 ripe banana

Bake

  • Bake for 35–40 minutes, or until a toothpick comes out clean and the top springs back lightly.
  • Let cake cool completely before frosting.

Make the Frosting

  • Beat 225 g cream cheese until smooth.
    225  g cream cheese
  • Add powdered sugar gradually, followed by vanilla and salt.
    180 –200 g powdered sugar, 5  g vanilla extract, Pinch of salt
  • Beat in the cooled brown butter until smooth and creamy. Chill 10–15 minutes if frosting is too soft.

Frost the Cake

  • Once the cake is completely cool, spread the frosting evenly over the top.
  • Slice and enjoy!

Notes

• Sourdough discard or active starter both work well.
• For added flavor and visual appeal, use banana slices on top before baking.
• Store frosted cake in an airtight container in the fridge for up to 5 days.
• This cake freezes well (without frosting) for up to 2 months.