Gluten-Free Whole Grain Banana Walnut Cake
Inspired by a recipe in a favorite cookbook, this Gluten-Free Whole Grain Banana Walnut Cake is lovely with an afternoon cup of tea or even as a mid-morning snack.
Gluten-Free Banana Walnut Cake
One of my favorite cookbooks is Kim Boyce’s Good to the Grain, a beautiful volume full of rustic, homey desserts and breakfast bakes incorporating whole grains and some gluten-free flours. I made her banana walnut cake two years ago when we were just getting to know our neighbors, now good friends, down the street — they’d invited us for dinner and I brought dessert, glad to have the excuse to bake a cake I’d been eyeing for awhile. It was so well received I knew I had to adapt it to be gluten-free and lower in sugar.
This is a simple, nubbly cake full of bananas and ground walnuts, a perfect winter weekend cake. Baking with bananas is a bit of a sugar cheat — I love them because they can work to sweeten a batter without needing a lot of additional sugar. My Aussie friend Katie and I recently had a text conversation about the versatility and beauty of bananas and she reminded me that a banana can even work as an egg in a pinch. In this recipe I’ve kept them as a flavor and sweetness enhancer, but I will keep that info in my back pocket for another time.
This is a lovely cake to put together — you just need sorghum and arrowroot to form your flour base, then fold in some toasted, ground walnuts for texture and heft. Just one-half cup of sweetener is needed, so the additional sugar is turned way down (hooray!). Yet the cake is certainly sweet enough, and the natural goodness of the bananas keeps it tasting like a treat. You’ll want very ripe bananas here; you can freeze them until you’re ready to use, then defrost at room temperature.
Why You’ll Love This Recipe
Loads of banana flavor. You’ll need four very ripe bananas for this recipe.
Whole grain and nut flours. Sorghum flour is a naturally gluten-free whole grain flour that, when paired with the walnut flour, brings a nice hit of protein and fiber to this cake.
Maple syrup. I used maple syrup to enhance the sugar and to bring extra flavor. Maple syrup is wonderful with the bananas and seems just right balanced the walnuts.
Gluten-Free Flours Needed
Sorghum Flour
Sorghum flour is similar to oat flour and is a wonderful, versatile naturally gluten-free flour.
Arrowroot Flour
Arrowroot, like tapioca flour, helps to bind and bring loft to gluten-free baking.
Ingredients in Gluten-Free Whole Grain Banana Walnut Cake
- Walnuts
- Sorghum flour
- Arrowroot flour
- Baking powder and baking soda
- Fine sea salt
- Unsalted butter: At room temperature
- Coconut sugar: You can use brown sugar instead
- Maple syrup
- Bananas: Let your bananas get nice and ripe so their flavor and natural sweetness really shines
- Eggs: Use large eggs
- Greek yogurt: Use plain whole fat Greek yogurt
- Pure vanilla extract
How to Make Gluten-Free Banana Walnut Cake
For the full instructions, see the recipe card at the end of this post.
- Toast and process the walnuts. When cool, process 1 cup walnuts in a food processor until finely ground.
- Whisk flours. Whisk or sift together the sorghum and arrowroot flours, baking powder, baking powder and salt. Stir in the ground walnuts.
- Cream butter. Cream together the butter, coconut sugar, and maple syrup for 3 minutes. Add bananas one at a time until completely smooth. Add eggs one at a time. Beat in yogurt and vanilla.
- Finish batter. Pour in flour mix and beat on low until combined.
- Preheat oven. Preheat oven to 350 F and grease and line an 8-inch pan with parchment paper. Pour batter in pan and cover with the reserved toasted walnuts.
- Bake cake. Bake for 50-60 minutes then let cool on a wire rack.
Hint: If you like, you can sprinkle a little extra coconut sugar across the top of the cake with the walnuts for a bit more sweetness.
Substitutions
- Walnuts – sub a nut of choice, such as almonds or pistachios
- Sorghum flour – try sorghum flour
- Arrowroot – try tapioca flour
- Coconut sugar – swap for brown sugar
- To make dairy-free – substitute coconut oil or your favorite non-dairy butter. Substitute your favorite non-dairy yogurt for the yogurt.
Storage
Store the cake in the fridge, well-covered, for 5 days. Eat straight from the fridge or bring to bring temperature before serving.
Tip
For this cake, use the ripest bananas you’ve got. You know, the ones no one wants to eat and which have been kicking around the kitchen counter for longer than you’d like to admit. Those are perfect.
FAQ
Ripe bananas are softer — thus easier to mash and blend into a batter — and perhaps even more important, sweeter. As the bananas ripen, the fruit converts starches to sugars, which makes them sweeter, more flavorful, and absolutely perfect for baking recipes.
You need four bananas to equal two cups of mashed bananas. So if you have a bunch of leftover frozen bananas, measure out two cups to make this recipe.
It absolutely is. Walnut flour is raw walnuts that have been ground into powder form. For this recipe we toast the walnuts first, then grind them until they are fine, but not so much that they turn into walnut butter.
Gluten-Free Whole Grain Banana Walnut Cake
Ingredients
- 2 cups walnut pieces
- ⅔ cup/100 g sorghum flour
- ⅓ cup/60 g arrowroot powder
- 1 tbsp baking powder
- ½ tsp baking soda
- ½ tsp fine sea salt
- ½ cup unsalted butter, at room temperature
- ¼ cup + 1 tsp coconut sugar divided
- ¼ cup maple syrup
- 4 medium-large very ripe bananas
- 3 large eggs
- ⅓ cup Greek yogurt
- 1 tsp pure vanilla extract
Instructions
- Heat oven to 350° F. Rub an 8 or 9-inch pan with butter and line with parchment. Spread walnut pieces on a baking sheet, place in the oven, and toast for about 10 minutes. Remove from oven and set aside to cool. Turn off oven.
- In a medium bowl, sift together the sorghum flour, arrowroot, baking powder, baking soda, and salt. Place one cup of the toasted walnuts in a food processor and process until finely ground. Add to the flour mixture and stir to combine.
- In a large bowl, using a mixer, beat the butter, ¼ cup coconut sugar, and maple syrup together for a few minutes until light and fluffy. Add the bananas and mix on medium speed until the bananas are broken down and smooth. Scrape down the bowl as necessary. Add the eggs one at a time and beat until thoroughly combined. Add the Greek yogurt and vanilla and mix well to combine.
- Pour in the walnut-flours mixture and mix on low speed until combined. If you can, let batter rest for 30 minutes. Finely chop the remaining 1 cup of walnut pieces.
- Scrape the batter into the prepared pan. Scatter the chopped walnuts evenly across the top of the batter, then sprinkle 1 teaspoon of coconut sugar across the walnuts.
- Place pan in the oven and bake for 50-60 minutes, until a toothpick inserted in the center comes out clean. Remove pan from oven, place on a rack, and allow to cool in the pan before turning out onto a wire rack. Cake can be kept, well- covered in the fridge, for 5 days.