Blueberry Crumb Cake

ambspin
Jul 29, 2025
4 min read

Updated: Sep 4, 2025

A soft, almond-scented blueberry cake topped with a brown sugar crumble

When summer hits, I find blueberries irresistible,* grabbing at least two pints every time I walk by them at the store. A superfood in their own right, they're perfect by themselves and in anything one can dream of--smoothies, muffins, a hand pie or three. After batches of muffins and scones made the rounds in June, I wanted to showcase this super berry in something a little more special: a crumb cake.

This cake originated with Butternut Bakery's Blueberry Sour Cream Coffee Cake, a beyond delicious recipe by Jenna Barnard that spotlights blueberries and includes a generous brown sugar crumble topping. Her recipe is the ultimate blueberry treat, and I sought to create a version that was a bit less sweet and contained more wholesome ingredients. I halved the crumble, reduced the sugar, and exchanged some of the all-purpose flour for almond and oat flours, and I couldn't be happier with the result.

What's in this blueberry crumb cake?

Blueberry Cake

All-purpose flour: provides most of the structure
Almond flour: adds nuttiness and moisture
Oat flour: adds nutrition and heft
Baking powder: helps the cake rise
Baking soda: reacts with the acid in the sour cream to help the cake rise
Kosher salt: balances the sweetness
Unsalted butter: provides moisture, richness, and flavor
Sugar: sugar is essential to cake
Egg: provides structure and richness
Vanilla extract: everything is better with vanilla
Almond extract: scents the cake with almondy goodness
Sour cream: creates a tender, tangy cake crumb
Blueberries: the star of the show
Lemon zest: enhances the blueberries with citrusy brightness
Cornstarch: absorbs excess moisture from the blueberries and helps them "float"

Crumble and Glaze

All-purpose flour: the crunchy part of the crumble
Brown sugar: the dominant flavor of the crumble
Sugar: crumble requires sweetness
Cinnamon: adds complexity to the flavor
Kosher salt: balances the sweetness
Unsalted butter: holds each crumbly bite together
Glaze (powdered sugar, milk, and lemon juice): an optional (and highly recommended) final, citrusy flourish

There are a number of steps to this recipe, but they are all simple:

Prepare the crumble and set aside.
Prepare the blueberries and set aside.
Whisk together the dry ingredients and set aside.
Cream together the butter and sugar. Mix in the egg, extracts, and sour cream.
Add the dry ingredients and half of the blueberries to the wet ingredients.
Spread the batter in the pan, and add the remaining blueberries on top.
Sprinkle the crumble onto the cake and bake.
Cool completely, glaze, and enjoy!

Blueberries are front and center in this cheerful cake, and the glaze, should you choose to add it (and I think you should), makes it extra special. With its tender base and crispy topping, this crumb cake is a lovely, blueberry-filled indulgence that complements a morning coffee as beautifully as it caps off a summer picnic.

**“You ought to have seen what I saw on my way*

To the village, through Mortenson's pasture to-day:

Blueberries as big as the end of your thumb,

Real sky-blue, and heavy, and ready to drum

In the cavernous pail of the first one to come!

And all ripe together, not some of them green

And some of them ripe! You ought to have seen!”

~Robert Frost, excerpt from "Blueberries" (1915)

Blueberry Crumb Cake Makes one 9-inch cake (10-12 slices)

Author: Ambika

This blueberry crumb cake is adapted from Butternut Bakery's incredible Blueberry Sour Cream Coffee Cake. In addition to reducing the sugar and adding almond and oat flours to the cake batter, I also use less of the crumble topping than the original recipe calls for. The result is a more nutritious, tender, almond-scented blueberry treat. I hope you enjoy it!

Total Time: 2-2.5 hrs Prep. Time: 25 mins

Ingredients

Crumble:

1/2 cup all-purpose flour
1/4 cup brown sugar, packed
1/4 cup sugar
1/2 teaspoon cinnamon
pinch of kosher salt
3 tablespoons unsalted butter, melted

Blueberry Cake:

3/4 cup all-purpose flour
1/2 cup almond flour
scant 1/2 cup oat flour
1 teaspoon baking powder
1/4 teaspoon baking soda
1/2 teaspoon kosher salt
6 tablespoons unsalted butter, softened
1/2 cup sugar
1 egg, room temp.
1/2 teaspoon vanilla extract
1/4 teaspoon almond extract
3/4 cup sour cream, room temp.
2 cups fresh blueberries, rinsed and patted dry
zest of 1 lemon
1 tablespoon cornstarch

Lemon Glaze (optional):

1/2 cup powdered sugar
1/2 tablespoon milk
1/2 tablespoon lemon juice

Helpful Equipment: 9" springform pan, parchment paper, silicone spoon

Directions

Line a 9"springform pan with parchment paper. Preheat the oven to 350°F.
Prepare the crumble: Whisk the flour, brown sugar, sugar, cinnamon, and salt together in a medium bowl. Stir in the melted butter until you see small and large lumps. Refrigerate the crumble while you prepare the cake.
Prepare the blueberries: Toss the blueberries with the lemon zest. Then toss them with the cornstarch and set aside.
Prepare the cake: In a large bowl, whisk together the all-purpose flour, almond flour, oat flour, baking powder, baking soda, and salt. Set aside.
In a separate bowl, use a mixer to cream together the butter and sugar until fluffy, 2-3 minutes. Mix in the the egg, vanilla extract, and almond extract. Then mix in the sour cream.
Add the dry ingredients to the wet ingredients. Just before everything is fully mixed, use a silicone spoon to stir in half of the blueberries.
Spread the thick batter into the springform pan. Evenly spread the rest of the blueberries on top of the batter. Then top evenly with the refrigerated crumble.
Bake: Bake for 45-50 minutes, or until a toothpick in the center comes out with a few moist crumbs. Cool in the pan on a wire rack at room temperature for at least 1 hour. After the cake is cool, release the cake from the springform pan.
Icing (optional): Whisk the together the powdered sugar, milk, and lemon juice. Drizzle over the cooled cake.