Blum’s Coffee Cake Recipe
It was Elaine’s birthday (our founder) a few days ago and we made her a Blum’s Coffee Crunch cake, she especially loves the honeycomb part. This cake was born at the Blum’s Bakery when the owners, Mortimer and Irving Blum, wanted to reduce the coffee waste generated by the end of the day. They mixed the coffee and sugar and made a honeycomb crunch, and also used it in their whipping cream for flavor. That combined with layers of sponge cake made this a delicious treat and a legendary sensation in San Francisco. Here is the recipe for you to enjoy.
Ingredients for Blum’s Coffee Cake
1 ¼ cups all-purpose flour
1 ½ cups sugar
½ teaspoon kosher salt
5 large eggs, separated, plus 2 large egg whites
2 tablespoons water
¼ cup canola oil
1 teaspoon vanilla extract
1 teaspoon cream of tartar
1 teaspoon grated lemon zest
1 tablespoon lemon juice
Ingredients for Coffee Crunch
2 ¼ cups sugar
1/3 cup espresso or strong brewed coffee
1/3 cup light corn syrup
1 ½ tablespoons baking soda
Ingredients for Coffee Whipped Cream
1 ½ cups chilled heavy cream
1 ½ teaspoons vanilla
1 ½ teaspoons instant coffee granules
Directions for Blum’s Coffee Cake
Set the oven to 350ºF.
Coat your round 9” cake pan with a nonstick baking spray. Sift together the flour and ¾ cup of sugar and salt into a medium bowl.
In the bowl of a stand mixer fitted with the whisk attachment whip the yolks and ¼ of the sugar on medium speed until thick and pale yellow, about 4 minutes. Gradually add the water, oil and vanilla, mixing well.
In a separate, large bowl, whip together the egg whites and beat until frothy. Add cream of tartar and beat until egg whites form soft peaks. Add the remaining sugar and beat until stiff and 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 the egg whites and gradually fold in the dry ingredients, about 1 cup at a time. Fold gently until well incorporated. Pour batter into the prepared pans and bake until springy and golden brown and a toothpick comes out clean. Let cool completely and release from pans to assemble the cake.
You’ll need a candy thermometer to make the coffee crunch. Use a non-stick silicone pad and have it ready on the surface where you’ll pour the mix. Combine sugar, syrup and coffee in a 4-6 qt heavy pot. Cook over medium high heat stirring occasionally with heatproof silicone spatula until mixture reaches 270º.
Once the mixture reaches 270ºF, increase the heat to high and stir constantly until the liquid reaches 305ºF. (Have your baking soda ready to go.) Remove from heat and quickly whisk baking soda into the mix. It will expand and aerate quickly, in a matter of seconds. Pour the crunch onto the non-stick silicone pad and allow to cool, undisturbed for at least 30 minutes. Don’t try to flatten the mix or anything, you want all the air bubbles in there to make a proper honeycomb texture.
Once the crunch cools chop with a knife into quarter sized, or smaller, pieces. This can be made ahead and stored in an airtight container at room temperature until you are ready to assemble the cake. (The crunch will last up to two weeks in proper container.)
For the frosting whip the cream and when soft peaks form slowly add the sugar and coffee granules and vanilla. Whip until the cream holds peaks, and is glossy and not runny.
Cut the cake in half horizontally with a serrated knife. Put frosting in the middle of the cake and sprinkle 1 cup of the smaller pieces of the crunch, make sure the whole surface is covered. Place the second piece on top and frost the whole cake. Once this is done cover the surface of the cake evenly. Press the pieces of the crunch on the sides and top of the cake, covering the whole thing in crunch pieces, and refrigerate until ready to serve. The cake is best enjoyed the day it is assembled. If you apply the crunch in advance it will start to melt and lose the brittle.
