This blueberry buttermilk upside-down cake is a stunner of a summer cake and couldn’t be easier to make either!
This is the cake of family secrets.
It’s the cake that will make all of the old bitties at the church fair nudge each other out of the way with oversized handbags in order to buy the sole one remaining from the cakes and pies table.
It’s the cake I can picture being baked up in a tiny southern Georgia kitchen when the thermometer is crossing 90 degrees at 8am so that it’s ready for tea at 4pm.
Maybe it’s the buttermilk that induces these visions. The buttermilk, that tends to be a secret ingredient that no one can put their finger on.
But needless to say, I’ve found the perfect white cake that I’ve been searching for.
It’s a tender – thanks to the cake flour and buttermilk – and delightful cake that, when made into a layer cake, as it should have been with the original recipe, would be a complete show-stopper of a cake.
The original recipe that was chosen for this week’s Project Pastry Queen was a 3-layer cake with Jack Daniels’ buttercream cake. But I changed it substantially recipe to this buttermilk blueberry cake because I honestly couldn’t bear the thought of having to resist a buttercream-encased layer cake sitting on my counter for the rest of the week.
So I scaled the recipe down to one layer. And then lined the bottom of the cake pan with blueberries. I topped the blueberries with the cake batter, leveled it off, and baked.
The strawberry summer cake I made a few years ago is similar to this blueberry cake. Let’s call it a 2nd cousin, shall we.
The Secret Ingredients to a Perfect Cake
Both cakes are single-layer cakes. Both include ripe and fresh summer fruit. But unlike this blueberry cake, the strawberry summer cake isn’t made with cake flour or buttermilk, both of which yield a super soft and tender cake. THESE are the secret ingredients to a perfect cake!
And they’re such basic ingredients too, aren’t they? Buttermilk (liquid, not dried) is available in most grocery stores these days. Or you can make your own by mixing 1 tablespoon of white vinegar or lemon juice into 1 cup of milk.
Cake flour may be a little more difficult to find. Many regular grocery stores carry it in the baking aisle these days but not all of them do. And if you live outside the U.S., I hear it’s virtually impossible to find. I order cake flour online from Amazon or directly from King Arthur Flour but if I have also made my own in a pinch when I’m out of it.
To make your own cake flour, you’ll:
- Remove 2 tablespoons of flour from every cup you need in the recipe
- Add 2 tablespoons of cornstarch to the flour in the bowl
- Sift or whisk the flour together with the cornstarch
Yup! It’s that easy to make your own cake flour!
That strawberry cake, while so so delicious, also doesn’t have that familiar tang that a buttermilk cake produces. And the top of that strawberry cake yields a more cobbler-esque texture since the berries are baked into the batter and the cake is served rightside-up without any frosting.
Because the berries for this blueberry buttermilk upside-down cake are baked on the bottom of the pan, they all burst open when baked, leaving you with a layer of jammy blueberries followed by that utterly soft and delicious white cake layer. I liken this cake a little to a peach cake tatin, except there’s no caramel component to this cake.
Not that this blueberry cake is missing a caramel component. Because really, it’s just perfect as is.
- 1 cup cake flour
- ¼ tsp baking soda
- ¼ tsp salt
- A heavy/slightly rounded ⅛ tsp baking powder
- ½ cup buttermilk (liquid, not dried)
- Zest of ½ lemon
- ½ cup (1 stick) unsalted butter, at room temperature
- ⅔ cup sugar
- 1 large egg white
- ½ tsp vanilla extract
- 1 to 1 ½ cups fresh blueberries, rinsed and dried (enough to almost cover the bottom of a 9-inch round cake pan)
- Powdered sugar, for dusting
- Place one of the oven racks to the center position of the oven. Preheat the oven to 350° F. Spray the bottom and sides of a 9-inch round cake pan with cooking or baking spray, place a circle of parchment paper over the bottom of the pan (on the spray), then lightly spray the parchment paper with more cooking or baking spray.
- In a medium bowl, whisk the flour, baking soda, salt, and baking powder together; set aside. Stir the lemon zest into the buttermilk, set aside.
- In the bowl of a stand mixer fitted with a paddle attachment, beat the butter and sugar on medium speed about 2 minutes, until light and fluffy. Scrape down the sides of the bowl. Add the egg white and vanilla and beat on medium speed for about 1 minute. Add about one-third of the flour mixture to the batter and beat on medium speed until just incorporated. Add about half of the buttermilk and beat on medium speed until just incorporated. Continue adding dry and wet ingredients alternately, scraping the bowl down and beating until incorporated after each addition. End with the dry ingredients; the batter should be thick and glossy.
- Spread the blueberries out in the bottom of the pan. Spoon the batter evenly over the blueberries and using an offset spatula, smooth the batter out to the sides of the pan.
- Bake for 25 to 30 minutes, until a toothpick inserted into the middle of the cake comes out mostly clean with just a few crumbs on the toothpick and the top is flat and lightly browned.
- Set the cake pan on a wire rack to cool for 10-15 minutes. Invert the cake onto the rack and allow to cool completely before transferring it to a cake plate, dusting with powdered sugar, and serving.
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