This soft and moist brown sugar oat flour cake is topped with a tangy Greek yogurt frosting that’s spiked with plenty of bright lemon zest. This cake is incredibly fluffy and even better, it’s naturally gluten-free!
Best Oat Flour Cake Recipe
It’s no secret that I love baking with oat flour. and this cake showcases this versatile, naturally gluten-free flour to perfection. I mean, just check out that crumb! This is no boring gluten-free bake that crumbles when you sink a fork into it. The combination of coconut oil and yogurt brings lovely moisture to this vanilla-scented cake that lasts and lasts, making it stand out from dry gluten-free cakes. The tangy Greek yogurt frosting spiked with lemon zest is the perfect finishing touch.
Why You’ll Love This Gluten Free Oat Flour Cake
Soft and fluffy with a gorgeous crumb, this gluten-free cake comes together in minutes. The lemony frosting is delicate and delicious and brings just the right amount of added flavor. Here’s why you’ll love this gluten-free oat flour cake recipe:
- Naturally gluten free – Oat flour, a gluten-free baking powerhouse, is gluten-free, as are all of the other ingredients in this recipe.
- Easy ingredients – You can make or buy oat flour, and the tablespoon of arrowroot flour is optional if you wish to keep this a one-flour gluten-free cake. The rest of the ingredients you’ll probably already have in the pantry!
- Adaptable – Make this recipe as written or see some of my adaptation suggestions below! You could even use it as a base for muffins!
Why Oat Flour?
Oat flour is my absolute favorite gluten-free baking and cooking flour. It’s naturally gluten-free (although you’ll want to buy certified gluten-free oats or oat flour if you have celiac) and performs beautifully in gluten-free recipes. It can often be used in a 1:1 swap by weight for all-purpose flour and is similar to whole wheat flour. Plus, you’ll get a punch of whole-grain goodness in every bite.
What You’ll Need
Here’s a glance at the ingredients needed to make this dreamy oat flour cake with lemon frosting. The full ingredient amount and detailed instructions are in the recipe card at the end of this post – this is just an overview.
- Oat flour – See my substitution suggestion below if you can’t have oat flour
- Arrowroot flour – This is an optional addition but gives a little extra lightness to the cake
- Brown sugar – I use light brown sugar but dark brown sugar or granulated sugar is fine, too
- Leavening agents – Baking powder and baking soda
- Salt – I always use fine sea salt in my recipes!
- Milk – Use whole milk for richness; 2% will work as well
- Yogurt – Use any kind of plain, regular yogurt
- Coconut oil – Or substitute another neutral oil
- Vanilla extract – Pure vanilla extract will give the best flavor
- Greek yogurt – You can use non-fat, low-fat, or whole-fat Greek yogurt
- Lemon – Use the zest of one whole lemon
- Powdered sugar – Make sure to sift the powdered sugar before you whisk it into the frosting to avoid any lumps
How to Make an Oat Flour Cake
- Make cake: Preheat the oven to 350ºF. Grease an 8×8-inch baking dish with coconut oil and line the bottom with parchment. Set aside.
- Whisk: Whisk together the oat flour, brown sugar, baking powder, baking soda, and salt. In another bowl, whisk together the wet ingredients. Combine.
- Rest: Pour the batter into the prepared pan and let it rest for 10 minutes.
- Bake: Bake for 35-40 minutes, until a tester inserted in the middle comes out clean.
- Make frosting: Whisk the Greek yogurt, lemon zest, and powdered sugar together, spread it over the cooled cake.
Tips & Substitution Suggestions
This is a wonderfully reliable recipe, and once you’ve mastered it you can start experimenting with other flavors and additions! Below, find a few tips, substitution, and variation ideas to get you started:
- Oat flour substitute – Use an equal amount of sorghum flour for the oat flour – sorghum flour is another wonderful gluten-free flour that has similar qualities to oat flour.
- Rest the batter – Don’t skip the step of resting the batter for 10 minutes! This is what helps the cake have such a plushy, fluffy crumb because the liquid helps to hydrate the oat flour, which then results in a better structure after it’s baked.
- Make it dairy-free – In the cake batter, substitute non-dairy milk or non-dairy yogurt for the yogurt. In the frosting, use non-dairy yogurt for the Greek yogurt.
- Make it refined sugar-free – Easily make this cake refined sugar-free by swapping coconut sugar for the brown sugar in the cake, and experiment with using maple syrup or honey in the frosting. Note that you’ll use less of a liquid sweetener than the powdered sugar.
- Make it egg-free – I have not experimented with making oat flour cake without eggs, but you could try substituting two flax eggs for the eggs, or even applesauce.
- Bake as cupcakes – If you wish, you can make this recipe as cupcakes! Line a cupcake tin with liners, fill them 2/3 full, and bake the cupcakes for about 20-25 minutes, until a tester inserted in the middle of a cupcake comes out clean.
- Try different frostings – This cake is a lovely jumping-off place for all sorts of flavor combinations. You could top it with a chocolate glaze, cream cheese frosting, a drizzle of caramel sauce, fluffy chocolate buttercream, or a simple dusting of powdered sugar.
- Add different citrus – Swap the lemon zest in the icing for lime, orange, grapefruit, or mandarin zest for a flavor twist.
- Make it a layer cake – Double the recipe and bake it in two parchment-lined 9-inch baking pans. Fill and frost the cake with jam, frosting, or whatever else you can think of.
- Add fruit – This would make a lovely fruit cake! Stir in 1 cup of raspberries, blackberries, blueberries, or a combination into the batter.
I love a square of oat flour cake with a cup of coffee or tea. It’s also lovely served with fresh fruit like sliced strawberries, or a combination of blueberries and raspberries. I prefer it as a simple dessert, although you could definitely add an oat flour cake to a brunch spread or nibble on a piece for a morning snack.
How to Store Oat Flour Cake
Here’s how to store your oat flour cake:
- Fridge – Because the frosting contains dairy, I recommend storing the cake in the fridge. Cover it with foil and keep it in the fridge for up to 5 days.
- Freezer – Chill the cake in the fridge to set the frosting, then wrap the whole cake or individual slices in plastic wrap then foil and place them in the freezer for up to 3 months. Thaw the cake completely in the fridge before serving.
More Gluten-Free Cake Recipes
Oat Flour Cake
For the Cake
- 2 ½ cups oat flour (280 grams)
- 1 tablespoon arrowroot flour optional
- ¾ cup light brown sugar packed
- 1 ½ teaspoons baking powder
- ½ teaspoon baking soda
- ¼ teaspoon fine sea salt
- 2 eggs
- ¾ cup whole milk
- ½ cup plain yogurt
- ¼ cup coconut oil melted
- 1 tablespoon pure vanilla extract
For the Frosting
- 6 tablespoons Greek yogurt
- 1 lemon zested
- 1 cup powdered sugar
Make the Cake
- Preheat the oven to 350ºF. Grease a 8X8-inch baking dish with coconut oil and line the bottom with parchment. Set aside.
- In a large bowl, whisk together the oat flour, brown sugar, baking powder, baking soda, and salt. In a medium bowl, whisk together the wet ingredients. Add the wet mix to the dry mix and stir well to combine (batter will be thin).
- Pour the batter into the prepared pan and let it rest for 10 minutes, while the oven heats.
- Place the cake in the oven and bake for 35-40 minutes, until a tester inserted in the middle comes out clean. Remove from the oven, cool in the pan on a wire rack for 15 minutes, then turn out on the rack to cool completely.
Make the Frosting
- When the cake is fully cooled, make the frosting: whisk the Greek yogurt and the lemon zest together, then sift in the powdered sugar and whisk to combine. Spread the frosting over the cake. Place the cake in the fridge if you wish to set the icing a bit.