I first fell in love with strawberry cake as a kid, when I had no defense against the allure of those fluffy pink layers presented by the Pillsbury Doughboy. It didn't bother my 12-year-old self that strawberry cake always came from a box; such was the origin of all cake in my world. But the more time I spent baking, the more pleasure I took in making things from scratch, slowly graduating from mixes to recipes over the years.
Yet even after culinary school, the strawberry cake of my childhood eluded me. Using fresh fruit, my best efforts always turned out more like muffins than cake, and the worst were horrifically gummy and dense. Either way, the cakes I produced were invariably a muddy maroon, never pretty in pink.
Those difficulties are why most recipes for "homemade" strawberry cake call for a box of strawberry Jell-O, as its industrial formulation is uniquely suited to mimicking that elusive strawberry flavor and color. But I'm not one to walk away from a challenge, and I couldn't let go of the notion that one could make a light and fluffy strawberry cake entirely from scratch.
It's been an on-again, off-again project of mine for years, but with the challenge of writing a cookbook behind me, I finally had the chance to buckle down and conquer it once and for all.
Few recipes have stumped me to the point of despair, but strawberry cake had me on the brink as I tried it over, and over, and over, and over again. Finally, my failures pushed me to change the one variable that had never changed: the strawberries.
Simply swapping them for an equal weight of blackberries (in the form of purée) made the cake an instant success—moist, tender, fluffy, and vibrant in every way.
That meant my underlying formula was sound. I've done a full write-up on that cake already, but in short: Puréed fruit furnishes the cake with a good mix of water, color, acidity, and flavor. Plain egg whites assist with structure and rise, while keeping the color and flavor pure. Bleached cake flour binds up all the liquids to ensure a fluffy crumb. Baking soda protects the fruit's natural color, while fueling the cake's stellar rise.
So what was it that made blackberries so uniquely suited for success? Their distinctive bite, a.k.a. acidity. My experiments with strawberry cake vastly overestimated how much acid the mellow berries contributed to the batter, which meant a good portion of the baking soda was left un-reacted. That prevented the cake from rising as it should, while excess alkalinity gave it a dull color and wonky flavor. By switching to tart blackberries, I increased the overall acidity, bringing the formula into balance.
To achieve the same success in my strawberry cake, I needed to adjust the pH by either dialing back the baking soda or amping up the acidity. The former was the simplest solution, but where's the fun in that? With the latter, I saw an opportunity to tart things up with more strawberries instead.
Since the success of my blackberry cake proved the recipe had the right amount of fruit purée for hydration, I knew adding more fresh strawberries would be out of the question. So I reached for freeze-dried strawberries instead.
Unlike fresh, frozen, or dried fruit, freeze-dried fruit has no moisture content at all, giving it a concentrated flavor, color, and acidity. Because they're crisp and dry, the freeze-dried strawberries can be ground into a fine powder with the cake flour for even distribution.
I started small, working my way up from half an ounce to a full three ounces of freeze-dried strawberries to see how my cake would behave. The sweet spot turned out to be two and a quarter ounces, which gives the batter enough additional acidity to react with the soda for a super-fluffy crumb and vibrant color, as well as an amazing boost to the flavor.
Aside from the strawberry flour, the cake is assembled more or less like my classic vanilla butter cake, with fresh strawberry purée standing in for the liquid ingredients.
To make the batter, cream the butter and sugar until the mixture is fluffy and pale, then add the egg whites, a little at a time.
Pause to scrape the stand mixer's bowl and beater, then resume mixing on low. Add a third of the strawberry flour, followed by a third of the purée, and so on until both have been fully incorporated.
Be sure to scrape the bowl and beater really well, then fold the batter a few times from the bottom up to make sure there are no unincorporated bits of butter or flour lurking in the mix. Not only will these give the cake a weird tie-dye effect, poor mixing will also prevent it from rising as it should.
Scrape the batter into parchment-lined eight-inch anodized-aluminum cake pans. I've talked about the importance of a good cake pan before, but it's especially crucial for acidic batters, which can easily discolor in the wrong type of pan.
My recommendation is a deep anodized-aluminum pan with a parchment liner to minimize crust development (though it's natural for some browning to occur, giving the top crust a more vibrant color than the crumb).
The cakes will be fragile while warm, so let them cool about an hour in the pans before inverting to peel off the parchment. While the strawberry cake can be frosted with whatever you like, from Swiss meringue buttercream to fruity whipped cream, I love it best with my thick and fluffy cream cheese frosting.
The tanginess of cream cheese really plays up the fruitiness of the strawberries, and the frosting's airy consistency is a perfect match for the lightness of the cake. It may not be as stiff as a traditional buttercream, but it's sturdy enough to fill and frost a layer cake (provided you don't plan on traveling with it in a car, as the butter-less frosting won't harden in the fridge).
For that reason, it's hard to pull off a traditional crumb coat with this creamy frosting, but that just means the layers can be stacked and frosted more casually instead.
If your heart is set on a more refined look, you can switch to a classic Swiss buttercream that can be sculpted into clean lines, but I think a rustic effect can be stunning, too.
I like to finish the cake with freeze-dried strawberries crumbled over the top, like flame-red sprinkles, though fresh strawberries will also work well.
Due to its unique formulation, this cake will spoil rather quickly at room temperature, so it's best enjoyed right away. If you need to hold it more than 24 hours, it should be wrapped in plastic and stored in the fridge.
Let the cake return to room temperature before serving, especially if it's frosted with a Swiss buttercream, which will seem greasy and hard if served too cool. Happily, my whipped cream cheese frosting stays soft and creamy even when cold, so if you raid the fridge for a midnight snack, you won't be disappointed.