Gluten Free Rhubarb Cake

I really love rhubarb, and I love the simplicity of this pretty gluten free rhubarb cake, a spice-kissed cousin to my gluten free strawberry almond cake (I added almonds here for a bit of crunch; you can omit them if you wish). The cake itself is soft yet sturdy thanks to oat + almond flours, and bakes up into gluten-free perfection every time. Drizzle with a simple lemon glaze for extra flavor or dust with a shower of sifted powdered sugar.

If you're a fan of rhubarb (like me!), don't miss my gluten free upside down rhubarb cake or gluten free rhubarb cream cake recipes.

What You'll Love

Early summer is for rhubarb, and when it hits, I'm making alllll the rhubarb things, from rhubarb jam to rhubarb strawberry cake, gluten free rhubarb crisp, and gluten free rhubarb scones! This cake is soooo lovely and a happy addition to my rhubarb recipe list. It's:

• So flavorful. Rhubarb has such a unique flavor, and the simplicity of the ingredients here lets it shine.
• Easy. This is a one-bowl recipe! Yay! Start by creaming the butter, oil, and sugar until fluffy to create a nicely aerated base for the cake, then layer in the rest of the ingredients.
• Gorgeously textured. I love the combo of almond and oat flours in cakes - together, they create a plush, tender-crumbed cake that's sturdy yet soft. No one will guess this is gluten-free.

Ingredients Needed

Here's a glance at everything you'll need to make this pretty cake. Make sure to scroll down to my recipe card at the bottom of this post for the full ingredient amounts and instructions!

• Butter - Unsalted butter is best!
• Oil - Any neutral oil works here, or you can use coconut oil.
• Eggs - Use large or medium eggs.
• Granulated sugar
• Oat flour - Learn how to make oat flour in your kitchen, pick up a package of (certified gluten free if needed) oat flour at the store, or substitute brown rice flour if you don't eat oats.
• Almond flour - Use finely ground almond flour for the best texture. Substitute another nut flour or gluten-free whole grain flour if you don't eat almonds.
• Baking powder
• Salt - Fine sea salt or table salt works.
• Spices - A mix of ground cinnamon and ginger.
• Rhubarb - Use fresh or frozen rhubarb. I like to slice then chop my rhubarb into smaller pieces, but you can leave it larger for more texture.
• Almonds - I like to scatter some sliced almonds over the top of the batter before baking, but you can leave these off if you prefer.

Variation Ideas

• Skip the almonds - I like the pretty, slightly toasty vibe the sliced almonds bring to this cake, but you can totally leave them off. Try drizzling with maple glaze for a hint of extra sweetness, or simply sift powdered sugar over the top.
• Add strawberries - Make a strawberry rhubarb cake by stirring ¾ cup chopped strawberries and ¾ cup chopped rhubarb.
• Citrus zest - Orange and rhubarb are a lovely, classic combo. Stir the zest of 1 orange into the batter, or try lemon for a slightly different flavor.

Tips & Recipe Notes

• Can I use frozen rhubarb? Yes, frozen rhubarb works great in this recipe. And, you can cut up the stalks directly from frozen without needing to defrost them.
• Room temp ingredients. This is a pretty simple cake, so to make it taste the best it can be, you want the batter to be light and fluffy. Bring the butter and eggs to room temperature before beating so that they really incorporate into the batter.
• Another fruit. Use this base recipe to make a gluten free blueberry cake or gluten free raspberry cake!
• Other flour. If you prefer, use a 1:1 gluten-free flour for the combination of oat and almond flours (use 2 cups/280 grams of a flour mix, like my homemade gluten free flour blend).
• Make it dairy-free. Substitute non-dairy butter for the butter to easily make this a dairy-free cake.
• Nuts. If you love a bit of crunch, stir ½ cup of chopped walnuts into the batter.

Proper Storage

• Counter - Cover the cake pan or plate with foil and store on the counter for up to 3 days.
• Fridge - The cake will last even longer in the fridge in an airtight container or tightly covered. I like it best at room temperature, so let it sit out on the counter for a bit before eating.
• Freezer - Wrap the cake or pieces of cake in plastic, then foil, and store in the freezer for up to 3 months. Thaw completely in the fridge before serving.