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Jan 14, 2023

Blum's Coffee Crunch Cake

Blum's Coffee Crunch Cake.. a lemon and vanilla chiffon cake with an espresso infused whipped cream frosting and coated with an airy and crunchy coffee honeycomb-like candy.

Blum's Coffee Crunch Cake slice in front of the sliced cake.

Blum's was a small chain of bakery/soda fountain shops in California (based in San Francisco) that closed in the 1970s. Its most beloved menu item was this coffee crunch cake.

The bittersweet candy coating was evidently created when a confectioner made a candy-making error. Instead of ditching the candy, he smashed it and used it to coat a cake.

whole Blum's Coffee Crunch Cake unsliced.

While the idea of lemon chiffon with a coffee flavored topping sounds kind of odd, it actually works! The candy on its own is kind of bittersweet, but when it's nestled in the sweet coffee flavored whipped cream, it mellows and adds just the right amount of texture to the cake. It's pretty spectacular.

The candy for this cake is made by adding baking soda to a mixture of sugar, coffee, and corn syrup that has been cooking on the stove until it reaches 310 degree. The mixture bubbles up a lot, so be sure to use a large saucepan. Even when you pour it out to cool, it continues to puff up.

You can make the candy for this cake up to two weeks in advance and keep it in an airtight container.

Blum's Coffee Crunch Cake Slice.

This is definitely a special occasion cake. 

The steps for making this cake:

  1. Make the coffee candy and let it cool. Once it has cooled, break it up in a zip sealed plastic bag by gently smashing it with a rolling pin. 
  2. Bake the chiffon cake. It's a single layer that you will slice in half when you are ready to frost the cake. I wrapped my baked cake in plastic wrap and froze it until I was ready to assemble the cake. 
  3. Make the espresso whipped cream frosting and frost the cake. Once you have frosted the cake, stick it in the refrigerator for an hour to set the whipped cream, lest it collapse under the weight of the candy. 
  4. Coat the cake with the coffee crunch candy and serve! 

Blum's Coffee Crunch Cake on a cake plate.

Hints and Tricks: 

This recipe also calls for adding espresso powder to the whipped cream frosting. It's an amazing secret ingredient, but I've always struggled with the way it hardens into a solid mass in the cupboard. I tried everything, including saving those silica packets to keep this from happening. 

You can add it back to a coffee grinder to turn it back into a powder, but it's not the same. Finally, I discovered that keeping the instant espresso jar in the freezer keeps it powdery. 

I love whipped cream frosting, but it is tricky when you are planning ahead. To stabilize it, you can add some instant pudding powder or Intant Clear Jel along with the sugar. There is also a product called Whip It made specifically for stabilizing whipped cream. 

Blum's Coffee Crunch Cake slice with the cake behind it.

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Blum's Coffee Crunch Cake

Blum's Coffee Crunch Cake
Yield: 12 slices
Author: Karen's Kitchen Stories
Prep time: 30 MinCook time: 1 HourInactive time: 3 HourTotal time: 4 H & 30 M
Blum's Coffee Crunch Cake.. a lemon and vanilla chiffon cake with an espresso infused whipped cream frosting and coated with an airy and crunchy coffee honeycomb-like candy.


For the Coffee Candy
  • 1 1/2 cups sugar
  • 1/4 cup brewed coffee
  • 1/4 cup light corn syrup
  • 1 tablespoon baking soda
For the Cake
  • 1 cup sugar
  • 142 grams (1 1/4 cup / 5 ounces) cake flour
  • 1 1/2 teaspoons baking powder
  • 1/4 teaspoon salt
  • 5 large eggs (including 3 separated), room temperature
  • 6 tablespoons unsalted butter, melted and cooled
  • 2 teaspoons vanilla extract
  • 1 teaspoon lemon zest plus 2 teaspoons lemon juice
For the Whipped Cream Frosting
  • 2 cups heavy cream, cold
  • 6 tablespoons sugar
  • 1 tablespoon instant espresso powder
  • 1 teaspoon vanilla extract


To Make the Coffee Crunch Candy
  1. Line an 8 inch square cake pan with parchment paper and spray the parchment with spray oil. The parchment should go up the sides of the pan and have an overhang.
  2. In a large saucepan over medium-high heat, heat the sugar, coffee, and corn syrup, stirring occasionally. Cook until the mixture reaches 310 degrees F. Add the baking soda and stir. The mixture will puff up, which is why you are using a large pan. Pour the mixture into the cake pan. Let cool completely.
  3. Place the hardened block into a zip-loc bag and close the "zipper." With a rolling pin, crush the candy into bite-sized pieces.
To Make the Cake
  1. Heat your oven to 325 degrees F with a rack set at the lower middle position.
  2. Spray or grease a 9-inch cake pan, line the bottom with parchment, and spray or grease and the parchment. Dust the parchment paper and sides of the pan with flour. Reserve 3 tablespoons of the sugar.
  3. In a large bowl, whisk together the flour, baking powder, salt, and the rest of the sugar. Whisk in two eggs, three egg yolks, melted butter, vanilla, lemon zest, and lemon juice until smooth.
  4. It the bowl of a stand mixer with the whisk attachment, whisk the remaining three egg whites on medium-low for about a minute, until foamy. Continue mixing on medium-high until you have soft peaks, about another minute or two.
  5. Fold 1/3 of the egg whites into the flour mixture. Once incorporated, gently fold the rest of the egg whites into the bowl until just combined.
  6. Pour the batter into the pan and bake for 30 to 40 minutes, until a toothpick comes out clean. Cool in the pan on a rack, then turn the cake out onto a wire rack to cool completely.
For the Whipped Cream Frosting and Assembling the Cake
  1. In the bowl of a stand mixer, whip the cream, sugar, espresso powder, and vanilla on medium-low for one minute. Increase the speed to medium-high and and whip until you have stiff peaks.
  2. Cut the cake into 2 layers using a long serrated knife. Place one layer on your cake platter and spread 2 cups of the whipped cream over the top. Place the second layer on top of the first, and spread the rest of the whipped cream over the top and sides of the cake. Gently press the candy into the sides and top of the cake. Serve.

Nutrition Facts



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Cake, Blum's Coffee Crunch
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Recipe adapted from The Perfect Cake: Your Ultimate Guide to Classic, Modern, and Whimsical Cakes.  There are over 240 recipes!!

First posted September, 2018 and updated January, 2023. 

Would you like to comment?

  1. This looks delicious and I will definitely try it.

  2. Looks great. Ours seems to be getting better and better every day in the refrigerator!

  3. It looks so yummy! I really appreciate your hints.

  4. Wow, this looks fantastic! I really wanted to make this one but it has been so humid here that I knew I wouldn't get the result I wanted, so I am looking forward to trying it when it cools down a little bit. Also, thanks for the tips, especially for the cream frosting.

    1. Thanks Felice. I'm pretty sure you made the right choice with the humidity.

  5. OK.. I'm in! I'll be making this! Thanks for sharing at our Cupcake & cake party for Celebrate365 Blog Party!

  6. Holy cow could this be any more amazing? The cake itself sounds great but that whipped frosting and crumb on top put it over the top!

  7. Oh wow! This looks amazing! I cannot wait to give it a try!

  8. Totally decadent with the center layer of cream and candy on top.

  9. How much baking soda for candy part? Recipe doesn’t list.

  10. I love the idea of the coffee candy! My favorite candy bar is a Coffee Crisp which is like a coffee Kit Kat but bigger. I am totally intrigued and might have to try this one! At the last try to make the candy.

    1. I'm not familiar with that candy but now I'm intrigued!

  11. This is a lot like the special occasion cake made by “Carman” upstairs at THE OLD SAN FRANCISCO STEAK HOUSE in San Antonio back in the day. The Candy Crunch Cake was the best, as was Carman!

  12. Previous comment about old San Francisco steak house Just saw comment about leavening name. I’m baaaack, :)). Susan Paden, Canyon Lake, Texas.


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