Every bite of this blueberry crumb cake is divine! It’s moist, not overly sweet, and filled with bursting blueberries. A true crowd-pleasing dessert made with hearty oat flour and unrefined sugar!

(Dairy-free and gluten-free friendly)

Blueberry crumb cake slices arranged on parchment paper with blueberries sprinkled around them.

I’ve never met a crumb cake I didn’t love. But this oatmeal version truly takes the cake (literally). It’s filled with bursting blueberries, hearty oat flour, and is naturally sweetened.

My family adores this cake and for good reason! It’s moist, not overly sweet, and so so yummy that you can hardly resist a second helping.

If you know me as a food blogger, than you know I love making healthier versions of decadent desserts. I usually use oat flour to make this happen because of it’s nutritional value and 1 to 1 ratio with regular flour.

It took quite a few tests to make sure this recipe reached perfection but I’m beyond pleased with the final results. If you love yourself a good crumbly cake, you’ll absolutely love a slice (or three 😉) of this irresistible dessert.

Now, let’s get baking!

Ingredients Needed

The line up of ingredients you’ll need to make this recipe happen: butter (vegan or regular), baking powder + baking soda, eggs, vanilla extract, coconut sugar, oat flour, sour cream, and fresh blueberries.

Let’s Make Blueberry Crumb Cake – Step by Step

First, whip the butter and sugar for 3 minutes (make sure butter is room temperature – not soft).
Add eggs one at a time to butter and sugar mix.
Then fold in vanilla and sour cream. Slowly add oat flour, baking powder + soda, and salt. Do not over-mix batter (very important).

Line an 8×8 inch pan with parchment paper, then pour and spread batter evenly in pan.
Layer blueberries over batter.
Use a fork to mix together crumble ingredients sprinkle on top. Bake 350F for 45-50 minutes – test with toothpick in center. Let cool for 10-15 minutes before lifting edges of parchment paper to remove and slice.

Important Tips to Remember

Butter temperature: after testing this recipe a few times, I realized it’s super important to make sure the butter for the cake and crumble topping is room temperature – meaning it’s soft at the touch but still holds it shape. It should not be super soft or melty. This can cause the butter to melt in the oven quickly and cause the cake to not bake properly.

Switch up the fruit: adjust this recipe to your liking, swap blueberries with fresh raspberries or blackberries instead.

Make your own oat flour: we love purchasing oat flour because it’s ground to perfection (and it’s easier!). You can also make your own by blending whole oats or quick oats until very fine flour texture.

Make it dairy-free: I have made this recipe successfully with dairy and without it. To make it completely dairy-free use vegan butter and vegan/dairy-free sour cream. The dairy-free version of this cake has identical taste and texture as the dairy version – so fear not. 🙂

Tips for Storing Leftovers & Freezing

Leftovers: keep leftover cake fresh by storing in a airtight container or ziplock bag for up to 3-5 days – chill in fridge to keep extra fresh.

Freeze: place cake in freezer ziplock bags and freeze for up to 1 month. Remove and let thaw at room temperature – heat in microwave or in oven to enjoy.

I truly hope you love this blueberry cake! We’ve not been able to stop making it over here. It’s a recipe fit for any occasion or event!

Happy baking, friends! xoxo

More Healthy Desserts to Try

Want more recipes like this delish crumb cake? You may also enjoy our Oatmeal Banana Coffee Cake and our Fluffy Blueberry Oatmeal Muffins. Both are equally tasty and surprisingly filled with healthy ingredients.