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Banana Crumb Cake Slice. Moist banana cake with cinnamon sugar filling topped with walnut oat crumble topping. Finished with maple glaze icing.
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Banana Crumb Cake

Meet the more sophisticated relative of banana bread. This Banana Crumb Cake is a moist banana cake with a cinnamon sugar filling and a crunchy walnut oat crumble topping.
Prep Time: 25 minutes
Cook Time: 1 hour
Total Time: 1 hour 25 minutes
Course: Breakfast, Dessert
Cuisine: American
Servings: 12 slices

Equipment

  • 9-inch tube pan with removable bottom
  • small food processor

Ingredients

Crumble Topping:

  • ½ cup (65 g) walnuts, lightly toasted*
  • ¼ cup (50 g ) dark brown sugar, packed
  • ¼ cup (30 g ) old fashioned oats (rolled oats)
  • ½ teaspoon ground cinnamon
  • ¼ teaspoon kosher salt
  • 2 Tablespoon (28 g) unsalted butter, cold

Filling:

  • 3 Tablespoon (38 g) dark brown sugar, packed
  • 3 Tablespoon (38 g) granulated sugar
  • ½ teaspoon ground cinnamon

Banana Cake:

  • 2 cups (260 g) all-purpose flour
  • 1 teaspoon baking powder
  • ¾ teaspoon kosher salt
  • ½ teaspoon baking soda
  • ½ teaspoon ground cinnamon
  • ¾ cup (170 g) unsalted butter, softened, room temp
  • ¾ cup (150 g) granulated sugar
  • 2 large eggs, room temp
  • 2 teaspoon (10 g) vanilla paste
  • 1 cup + 2 Tbsp (260 g) mashed ripe banana (3 small bananas or 2 medium bananas)
  • 3 Tablespoon (45 g) sour cream, room temp

Maple Glaze Icing:

  • 1 cup (113g ) confectioners sugar (powdered sugar), unsifted
  • 1 Tablespoon dark maple syrup
  • 1 Tablespoon milk, or more depending on desired consistency
  • pinch kosher salt

Instructions

Crumble Topping:

  • Place walnuts, brown sugar, oats, cinnamon, and salt in a food processor. Quickly pulse 3 to 5 times until walnuts are coarsely chopped. Add cold cubed butter. Pulse another 3 to 5 times until mixture is crumbly. Set aside.

Filling:

  • In a small bowl, whisk together brown sugar, sugar, and cinnamon. Set aside.

Banana Cake:

  • Preheat oven to 350°F. Butter and flour 9-inch tube pan with removable bottom. Tap out any excess flour. For easier unmolding, line bottom of tube pan with parchment paper. Set aside.
  • In a medium bowl, whisk together flour, baking powder, salt, baking soda, and cinnamon. Set aside.
  • In a large bowl, cream together butter and sugar until smooth. Add eggs and vanilla. Mix until incorporated. Add mashed bananas. Mix until combined. (Batter may look curdled.)
  • Add half of dry mixture. Mix on low speed until batter starts to form. Scrape down sides of the bowl as needed to ensure thorough mixing. Mix in sour cream. Follow with remaining half of dry mixture. Mix until just combined and there are no longer any dry streaks of flour.

Assembly:

  • Add half of cake batter to prepared tube pan. Spread into an even layer. Sprinkle cinnamon sugar filling over cake batter. Top with remaining half of cake batter. Spread into an even layer. Sprinkle crumble topping over cake batter.
  • Bake for 50-60 minutes until crumble topping is golden brown and toothpick inserted in center of cake comes out clean. Allow cake to cool in tube pan for 15-20 minutes. Run mini offset spatula along perimeter of cake to loosen from tube pan. Unmold cake and transfer to wire rack. Cool to room temperature (30-90 minutes). Unmold cake from tube pan bottom.
  • Dust with powdered sugar before serving, or drizzle maple glaze icing on top.

Maple Glaze Icing:

  • In a small bowl, combine confectioners sugar, maple syrup, milk, and salt. Stir until smooth. If glaze is too thick, add another milk 1 teaspoon at a time until desired consistency is achieved.
  • Drizzle glaze over room temperature banana crumb cake. Allow icing to set, or enjoy immediately.

Notes

Toasting Walnuts: Place walnuts on a parchment lined baking sheet. Bake for 7-9 minutes in a preheated 350 degree F oven until lightly toasted. Rotate pan midway through baking to ensure even toasting. Allow walnuts to cool before adding with other ingredients. 
Storage & Leftovers:
  • Allow cake to completely cool to room temperature before storing. Unglazed cake can be covered tightly with plastic wrap until ready to serve.
  • Glazed cakes should be stored in an airtight container at room temperature. This banana cake can be held at room temperature for up to 3 days.
  • For longer storage, keep in the fridge for up to 5 days.
  • Enjoy sliced banana cake chilled, at room temperature, or warmed up.