Oat Flour Cake

It's no secret that I love baking with oat flour (check out my ultimate guide to baking with oat flour to see what I mean), and this sweet little 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 here brings lovely moisture to make it stay fresh longer, and makes it stand out from dry gluten-free cakes. The tangy Greek yogurt frosting spiked with lemon zest is the perfect finishing touch. For a chocolate slant, try my oat flour chocolate cake!

Why You'll Love It

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. (If you're wondering, is oat flour gluten-free?, it absolutely is.)
• 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?

Whole grain 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. Try it in oat flour scones, oat flour blueberry muffins, and more.

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 - Learn how to make oat flour or pick up a package at the store. If you can't eat oats, try brown rice flour or sorghum flour.
• Arrowroot flour - This is an optional addition, but it gives a little extra lightness to the cake.
• Brown sugar - I use light brown sugar, and 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!
• Eggs - Large eggs are best.
• 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.

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, substitutions, and variation ideas to get you started:

• 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 ⅔ 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.

Serving Suggestions

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

• 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.