Baking A Childhood Favorite: Blum’s Coffee Crunch Cake
If you grew up way back when in San Francisco like me, no doubt you grew up obsessed with Blum’s coffee crunch cake.
This neighborhood bakery was famed for this airy two-layer cake slathered inside and out with swirls of coffee whipped cream. The piece de resistance? The shellacking of crunchy toffee pieces all over it.
It was the cake families bought for birthdays, and all manner of other celebrations. Mine certainly did. That cake was always front and center for my birthday, as well as my two brothers’.
The secret was that you had to eat as much of it as you could that very first day. Because once refrigerated overnight, the toffee pieces turned soft and soggy, and not nearly as appealing. So I cop to always cutting myself a rather gargantuan piece as a child. It’s a wonder my parents let me get away with that, let alone eating a coffee-laced product at that age, when they’d never let a brewed cup itself pass my lips.
Thank goodness they did, too, because that cake remains an iconic part of my childhood. Just the thought of it is enough to make me smile big-time.
Blum’s is no more, unfortunately. But my Dad was thrilled to discover years ago that Yasukochi’s Sweet Stop in San Francisco’s Japantown baked a similar cake. He’d buy it now and again to surprise us with.
On a trip to Southern California, I was even more ecstatic to discover the version by Valerie Confections in Los Angeles.
This may be heresy, but I think it’s even better than the original Blum’s one. That’s because the toffee is slightly different. While the Blum’s cake was covered with small flat, hard sugary shards, Valerie’s is shrouded in big, airy, thick, crunchy honeycomb toffee. What’s more, this honeycomb toffee holds up better, so that if you have leftover cake the next day, it’s nearly as good as the first day.
I know, because I made the cake.
Yes, I made Valerie’s version of it, using her recipe.
The cake may look fancy and intimidating, but it’s really not that taxing. You can make the coffee crunch toffee the day before, and store it in a sealed container and hit will hold its crispness. The toffee is essentially a caramel flavored with brewed coffee to which you add baking soda at the last second. That’s when things get really exciting. It will foam up and double in volume. So, you have to work quickly to dump it out into a greased pan. Once completely cooled, you break it up into shards for the cake. You may end up with some leftover coffee crunch. Eat it by the handful like candy or sprinkle it on ice cream if you like.
The chiffon cake batter must be baked in a springform-like cake pan. I’ve seen people write online that they have used a regular cake pan, filling it to the brim. But just be warned that the batter will rise even to the top of the taller springform pan as it bakes, before settling down, so you want to use a pan with depth or else you risk spillover.
I found that the bottom of my cake browned more than I like, while the top was fine. The next time I make this cake, I will line the springform pan with a greased circle of parchment paper to add a little more protection. I adapted the original recipe to include that recommendation.
The cake is airy and light — a perfect match for the heavenly coffee whipped cream it’s covered with.
You apply the honeycomb toffee pieces all over the cake right before serving. That way they stay as crisp as they can. I baked the cake and frosted it, and transported it to my in-laws house for Christmas, toting the toffee in a separate container.
When it was all garnished, and brought to the table, it was a true sight to behold. It’s so unusual looking with its big, bold, craggy toffee armor, that it’s quite unforgettable.
None of my in-laws, who grew up in Sacramento, were familiar with the lore and love of this cake. But after one slice they were smitten.
You will be, too. It’s a taste memory that can’t help but live on oh-so sweetly.
Blum’s Coffee Crunch Cake
For Chiffon Cake:
1 1/4 cups (6.25 ounces) all-purpose flour
1 1/2 cups (10.5 ounces) sugar
1/2 teaspoon kosher salt
5 large eggs, separated, plus 2 large egg whites
2 tablespoons water
1/4 cup (2 ounces) canola oil
1 teaspoon vanilla extract
1 teaspoon cream of tartar
1 teaspoon grated lemon zest
1 tablespoon lemon juice
For Coffee Crunch:
2 1/4 cups (15.75 ounces) sugar
1/3 cup (2.66 ounces) strong brewed coffee
1/3 cup (3.75 ounces) light corn syrup
1 1/2 tablespoons baking soda
For Coffee Whipped Cream:
2 1/2 cups (20 ounces) well-chilled heavy cream
2 1/2 tablespoons sugar
2 1/2 teaspoons vanilla extract
2 1/2 teaspoons instant coffee granules
To Make the Cake: Position a rack in the center of the oven and heat the oven to 350°F. Coat the bottom and sides of a 9-inch round cake pan with a removable bottom (such as a springform pan) with nonstick baking spray. Cut a parchment round to cover the bottom of the pan. Spray that with nonstick baking spray, too.
Sift together the flour, 3/4 cup of the sugar, and the salt into a medium bowl.
In the bowl of a stand mixer fitted with the whisk attachment (or in a large bowl, using a handheld mixer), whip the yolks and 1/4 cup sugar on medium speed until thick and pale yellow, about 4 minutes. Gradually add the water, oil, and vanilla, mixing well. If using a stand mixer, transfer the mixture to a large bowl and wash and dry the mixer bowl and whisk (or wash the beaters).
Add the egg whites to the large mixer bowl (or another bowl) and beat until frothy. Add the cream of tartar and continue beating until the egg whites form soft peaks. Add the remaining 1/2 cup sugar and beat until stiff, glossy peaks form. Add the lemon zest and juice and beat just until incorporated, about 15 seconds.
Using a rubber spatula, fold the yolk mixture into the egg whites. Gradually fold in the dry ingredients, approximately 1 cup at a time, until fully incorporated.
Pour the batter into the prepared cake pan and smooth the top with a spatula. Bake the cake for 55 minutes to 1 hour, until it is golden brown and a toothpick inserted in the center comes out clean.
Let the cake cool completely on a cooling rack, about 45 minutes (removing the cake when it is still warm will cause it to deflate and likely tear).
Run an offset spatula around the sides of the cake to loosen it from the pan. Holding the rim of the pan with one hand, press the bottom of the pan up and out. Run an offset spatula between the cake and the bottom to release it. Wrap the cake in plastic wrap and refrigerate until you are ready to assemble the cake.
To Make the Coffee Crunch: Attach a candy thermometer to the side of a 4- to 6-quart heavy pot. Add the sugar, coffee, and corn syrup to the pot and cook over medium-high heat, stirring occasionally with a heatproof silicone spatula until the mixture reaches 270°F, about 10 minutes.
Meanwhile, heavily coat a 13-by-18-by-1-inch baking sheet with nonstick baking spray. Measure the baking soda into a ramekin or cup and place near the stovetop, along with a large whisk.
When the crunch reaches 270°F, increase the heat to high and stir constantly until the crunch reaches 305°F. Remove from the heat and quickly whisk the baking soda into the crunch; the mixture will expand and aerate quickly, in a matter of seconds. Pour the crunch onto the baking sheet. Allow the crunch to cool, undisturbed, for at least 30 minutes.
Using a cleaver or other heavy knife, chop the crunch into quarter-sized pieces. (The crunch can be made ahead and stored in an airtight container at room temperature for up to 2 weeks.)
To Make the Coffee Whipped Cream: Combine the heavy cream, sugar, vanilla, and coffee in a large bowl and whip with a handheld mixer until medium peaks form.
To Assemble: Place the cake on a turntable or cake stand and, using a long serrated knife, slice the cake horizontally in half. Remove the top half and place cut side up on a plate. Cover both halves with whipped cream, using approximately 1/2 cup per side. Scatter 1 cup of the crunch evenly to cover the bottom half. Place the top half, cream side down, on the top of the crunch layer and press gently to even the layers. Frost the sides and top of the cake with the remaining whipped cream. Refrigerate until ready to serve.
When you are ready to serve the cake, cover the sides and top with the remaining crunch (if you apply the crunch in advance, it will start to melt and lose its bite).
This cake is best enjoyed the day it is assembled. Store it in a cake box or under a cake dome in the refrigerator.
Adapted from Valerie Gordon of Valerie Confections