Martha Stewart Blum’s Coffee Crunch Cake

Martha Stewart Blum's coffee crunch cake takes about 2 hours 20 minutes and a few pantry staples to make a light lemon-vanilla sponge with coffee frosting. It's an easy San Francisco bakery dessert for birthdays, Mother's Day or holiday dinners, and it's a showstopper that feeds a crowd.

Fold the beaten egg whites into the batter in two additions, gently but thoroughly, because that is what keeps the sponge tall and airy. Stir them in hard and the cake bakes up dense instead of light.

Martha recreates the famous Blum's Bakery cake from San Francisco, so the sponge is a light tube-pan cake rather than a heavy layer cake. Coating the sides and top with coffee crunch just before serving keeps the candy shards sharp and crisp against the soft frosting.

Martha Stewart Blum's Coffee Crunch Cake

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Course: DessertCuisine: AmericanDifficulty: Medium

Servings

12

servings

Prep time

20

minutes

Cooking time

1

hour 

Calories

450

kcal

A tall, airy sponge cake gets covered in smooth coffee frosting and crowned with crisp, shattering coffee candy. The soft cake and the crunchy topping make every slice a mix of light and brittle.

Ingredients

• 2 1/4 cups cake flour (not self-rising)
  

• 1 1/2 cups sugar
  

• 1 tablespoon baking powder
  

• 1 teaspoon kosher salt
  

• 1/2 cup vegetable oil
  

• 6 large eggs, separated
  

• Zest of 1 lemon
  

• 1 tablespoon pure vanilla extract
  

• Coffee Frosting
  

• Coffee Crunch
  

Directions

• Preheat and mix batter: Preheat the oven to 325 degrees. Whisk 2 1/4 cups cake flour, 3/4 cup sugar, 1 tablespoon baking powder and 1 teaspoon kosher salt in a large bowl, then add 3/4 cup water, 1/2 cup vegetable oil, 6 egg yolks, the zest of 1 lemon and 1 tablespoon vanilla extract and beat until smooth.
• Whip the egg whites: Whisk the 6 egg whites in a mixer fitted with the whisk attachment on medium-high speed. With the machine running, add the remaining 3/4 cup sugar in a slow, steady stream until stiff, glossy peaks form.
• Fold and bake: Take the bowl off the mixer and fold the whites into the batter in two additions, gently but thoroughly. Pour it into a 10-inch tube pan and bake about 1 hour, until a toothpick in the center comes out clean.
• Cool upside down: Invert the pan onto a narrow-necked bottle if it doesn't have feet. Let it stand until cool, about 1 hour, before removing the pan.
• Frost and finish: Set the cake on a serving platter and cover it with an even layer of coffee frosting. Just before serving, sprinkle the top and sides generously with coffee crunch.

Tools for this recipe

• KitchenAid Artisan 5-quart stand mixer, Chicago Metallic angel food tube pan, removable center, OXO silicone spatula set, Nielsen-Massey Madagascar Bourbon vanilla extract, 8 oz. As an Amazon Associate I earn from qualifying purchases.

FAQs

Can I use all-purpose flour instead of cake flour?

Cake flour is what gives this sponge its light, tender crumb, so I'd stick with it. If you only have all-purpose, the cake will be a bit tougher and chewier. The recipe also says not to use self-rising, since it already contains leavening.

Do I need a tube pan for this cake?

Yes, the 10-inch tube pan helps the tall sponge bake evenly and hold its shape. If the pan has no feet, flip it over onto a narrow-necked bottle to cool. Hanging it that way keeps the airy cake from collapsing.

When should I add the coffee crunch?

Add it just before serving, as the recipe says. The candy pieces soften when they sit against the moist frosting. Sprinkle generously over the top and sides so every slice gets some crunch.

Can I make the cake ahead of time?

You can bake the sponge a day ahead, let it cool completely, and cover it well at room temperature. Frost it and add the crunch shortly before you serve it. That keeps the frosting fresh and the candy crisp.

What's the most common mistake with this cake?

Deflating the egg whites is the big one. Beat them to stiff, glossy peaks, then fold them in gently in two additions. Over-mixing knocks out the air and leaves you with a dense, heavy sponge.