Tender and buttery and bursting with pockets of ripe summer berries, this blackberry butter cake is what I’d call an ideal snack cake—a snackberry cake, if you will—that’s easy to prepare and even easier to eat.
Sometimes simple is best, and this blackberry cake is proof in its perfection, no fancy frostings or fillings needed! It comes together quickly with minimal time and effort (remembering to get your ingredients out ahead of time is probably the hardest part), and the result is a casual yet impressive muffin-like cake that’s a perfect way to use up those summer berries.
The recipe is loosely based on my trusty sour cream coffee cake recipe, with slightly different proportions to accommodate the berries in an 8-inch square pan. And hey, if you want to call it a coffee cake and eat it for breakfast, I’m not going to judge you (it’s basically a muffin masquerading as a cake).
Using sour cream is really my favorite way to get a moist and flavorful butter cake; the fat adds moisture and flavor, and the acidity balances out the sugar. (Psst, sour cream also makes for an awesome chocolate cake too).
The dusting of granulated sugar on top makes for a delightfully crispy finish, without the need for a separate crumb mixture (as much as I love a crumb topping, I don’t love the extra dishes it creates). In fact, this cake can practically be prepared in a single bowl, either the bowl of a stand mixer or a large mixing bowl with an electric mixer.
Interestingly, I first tested this cake with just baking powder in it, and while the resulting cake had a wonderful flavor and a soft, pillowy texture, the top of the cake was entirely pale with barely any color to it at all. Using a mix of baking powder and baking soda (which is doable here because the sour cream provides an acid for the baking soda to react with), results in a golden brown top due to what’s known as the Maillard reaction. Just a little baking science for you!
You’ll notice that this recipe has you mix the baking soda into the sour cream, rather than with the dry ingredients. This unique step produces a particularly light and airy cake!
As with any creamed-butter cake, temperature matters! Let your eggs, butter, and sour cream come to room temperature before you start baking (in the summer, that means 30-60 minutes at least, longer in the winter or in cooler climates). Ensuring your ingredients are all the same temperature will give you a beautifully emulsified batter that bakes with a perfectly even crumb throughout.
To quickly bring up eggs to room temperature, submerge them in lukewarm water for 15 to 20 minutes.
Sinking berries is one of the main problems with most berry-filled cakes. Blackberries in particular, because they are so large, are extra prone to sinking (leaving oddly shaped pockets in the top crust rather than visible berries).
To prevent the berries from sinking, be sure they are fully dried (I lay them out in a single layer on paper towels for 20 minutes or so before I start baking) then toss with a light dusting of flour helps them ‘float’ within the batter rather than sinking to the bottom.
Also, instead of folding the berries into the batter, arrange them between layers of batter. This results in better berry float, not to mention more even distribution and no smears of purple in the cake either (that’s a triple win!) The layering technique also helps ensure the large berries are distributed evenly throughout the entire cake, guaranteeing you get a little bit of berry in each and every bite.
This recipe would work equally well with blueberries or even raspberries (strawberries have too much moisture which leads to soggy pockets… though you could use the maceration trick from my strawberry banana bread which draws out some of the moisture from the berries). If you use smaller berries like blueberries, you can fold the flour-dusted berries into the bulk of the batter rather than layering them.
Ingredient Notes & Substitutions
Blackberries: small, firm, tart blackberries work best in this recipe. Sometimes blackberries can be enormous and it just makes it a bit harder to layer them in the batter (though the layering technique makes it possible either way). You can also sub raspberries or blueberries in this recipe if you like!
Sour cream: adds moisture and richness as well as a suitable acid to react with the baking soda. Full fat greek yogurt can be used instead, however the cake will be a little drier due to the reduced fat. Just please don’t use nonfat yogurt in this recipe.
Almond extract: while this cake isn’t overly almondy, just a tiny bit of almond extract compliments the vanilla and blackberry, and gives the cake a more interesting depth of flavor. That said, you can omit it if you like.
If you’d rather have a hint of lemon instead of a hint of almond, rub a bit of lemon zest into the sugar before beating it with the butter. I think a lemony version of this cake would be lovely!
Blackberry Butter Cake
Tender and buttery and bursting with pockets of ripe summer berries, this blackberry butter cake is what I’d call an ideal snack cake—a snackberry cake, if you will—that’s easy to prepare and even easier to eat.
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Preheat oven to 350 degrees F. Line the bottom and sides of an 8-inch square cake pan with parchment paper; lightly butter parchment.
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Wash blackberries and spread on a paper-towel lined plate to dry fully.
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Measure out flour into a small bowl, and whisk with baking powder and salt (baking soda will be used in a different step).
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In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, cream butter and sugar together until fluffy, 2 to 3 minutes. Add eggs, one at a time, mixing well after each addition.
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Whisk baking soda into sour cream (I recommend measuring your sour cream with a 1 cup liquid measuring cup, then you can whisk the baking soda right in without dirtying another bowl).
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Add half of dry ingredients to the stand mixer bowl, and mix on low speed until almost but not quite fully incorporated. Add all of sour cream mixture along with vanilla and almond extracts and mix to combine. Scrape down the sides of the bowl, then add remaining flour and mix on low speed, or by hand, until just incorporated.
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Toss blackberries with a teaspoon or two of flour until lightly coated (don’t do this too far ahead of time or the flour will get gummy).
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Spread or scoop half of the batter into prepared baking pan, spreading into an even layer. Top with half of blackberries, spacing them out evenly if possible.
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Dollop remaining batter on top of berries, gently spreading into an even layer with an offset spatula.
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Top with remaining half of blackberries, positioning them in the spaces between berries from the first layer, especially if your berries are on the large side. Sprinkle generously with a tablespoon or so of granulated sugar.
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Bake for about 38 to 42 minutes or until top is light golden brown and a toothpick inserted near the center (try not to stick it into a berry) comes out clean.
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Place pan on a wire rack to cool. Then use the parchment to lift the cake from pan to cool completely before slicing into squares. Cake will keep, covered in an airtight container, for up to 3 days.
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