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Gluten-Free Banana Cake with Peanut Butter Penuche Frosting

Buckwheat adds a nice texture and flavor to this gluten-free banana cake. The peanut butter frosting is absolutely scrumptious.

  • Total Time: 1 hour
  • Yield: 10-12 1x


Units Scale
  • For banana cake:
  • 1 1/4 cups granulated sugar
  • 1 cup buckwheat flour (or 2 1/2 cups all-purpose wheat flour for all of the gf flours)
  • 1/2 cup sweet (glutinous) rice flour
  • 1/2 cup tapioca starch
  • 1/2 cup sorghum flour
  • 1 1/2 tsp. baking powder
  • 1/2 tsp. baking soda
  • 1 tsp. salt
  • 1/4 tsp. xanthan gum (omit if using wheat flour)
  • 1/2 cup cool or room temperature butter (use vegetable shortening or Earth Balance for vegan)
  • 1 cup mashed banana (from about 2-3 really ripe bananas)
  • 2/3 cup sour cream (for vegan use sour cream substitute, non-dairy yogurt or soured non-dairy milk)
  • 2 large eggs (for vegan use flax eggs or egg replacement powder)
  • 1 tsp. vanilla extract
  • For frosting:
  • 6 oz. salted butter (for vegan, use Earth Balance)
  • 1/2 cup brown sugar
  • 1/2 cup peanut butter
  • 4 cups or more powdered sugar
  • 1 tsp. vanilla extract
  • milk or water, about 1/4 cup


  1. For banana cake: Preheat oven to 350 degrees F. Grease two 9″ round cake pans and dust with a little buckwheat flour. Line the bottom of each pan with a round of waxed paper or parchment.
  2. Sift the dry ingredients together into the bowl of a stand mixer, or large mixing bowl if using a hand-mixer.
  3. Whisk together the banana, sour cream, eggs and vanilla extract. Set aside.
  4. Add the butter to the dry ingredients and turn mixer onto low. Mix just until butter is in small pieces. (It will look like when you’re making biscuits.)
  5. With the mixer running, add the banana/sour cream mixture. Beat on medium speed for about 2 minutes. Scrape down the sides of the bowl and turn mixer on for a few more seconds. Divide batter between the pans, smooth the top, and place in oven.
  6. Bake for about 30 minutes, or until the tops spring back when lightly pressed and a cake tester inserted into the center comes out clean.
  7. Let cool in the pans for about 10 minutes, then carefully run a thin knife around the inside of the pan to loosen the cake and turn out gently onto a cooling rack. Let completely cool.
  8. For frosting: Melt butter in a pan and let cook until the butter turns golden brown and smells wonderful. (If using vegan butter, just let it melt, don’t try to brown it.) Remove from heat so it doesn’t burn. Add the brown sugar. It will bubble up a bit. Stir until the brown sugar is dissolved. Add the peanut butter and stir well. Let sit for a few minutes until just barely warm. Transfer to a large mixing bowl and stir in vanilla.
  9. Using an electric mixer, beat in the powdered sugar, alternating with a little milk or water. Beat on high speed until the frosting is very thick and starts to set up like fudge. (It might start to look like it’s separating, add a little more powdered sugar and milk and keep beating.) If the frosting hasn’t set up, chill it for about 15 minutes in the fridge and beat again.
  10. To assemble cake:
  11. Remove the waxed paper from the first cake layer and place it on a serving platter. Top with about 1/2 cup of the frosting and smooth it out with an icing spatula to the edges. Top with the next layer. Place in the freezer for a few minutes so the icing can set.
  12. Place more of the frosting over the top of the chilled cake and use the icing spatula to spread it to the edges and down the sides of the cake. Turn the cake around while holding the spatula against the side of the cake to create a crumb coat. Chill again for a few minutes in the freezer.
  13. Spread the rest of the frosting (you might not need all of it) over the cake for the final layer. Let chill until ready to serve. (Any leftover frosting quickly disappears spoonful by spoonful.)
  14. Makes one 9″ round cake, 8-10 servings.
  • Author: Lindsey Johnson
  • Prep Time: 30 mins
  • Cook Time: 30 mins
  • Category: Dessert
  • Cuisine: American