I have been looking for a cake made honeycomb caramel for quite some time, so when I stumble upon Serious Eats‘ Blum’s coffee crunch cake, I knew that would be it. The honeycomb caramel has a unique texture, when you eat it, it crumbles in your mouth because small air bubbles are trapped in it, forming little holes (like in bee’s honeycombs, hence the name!). I really wanted to test this unique caramel texture!
And I found this Blum’s Coffee Crunch cake: apparently a mythical cake of the Blum’s Coffee in San Francisco, which closed down in the 70s (no need to mention that we will never what the original was like). As soon as I saw this cake I found it gorgeous with its coffee honeycomb look. Best of all, the base is a super light lemon chiffon cake that surprisingly complement the coffee whipped cream. I was afraid that the coffee honeycomb would just be there for decoration but it definitely contributes to the flavours and texture of the cake, providing a delicious crunch. This Blum’s coffee crunch cake is a complete marvel for the eyes and the taste buds!
Prep time: 40mn
Cook time: 1h15m
- 170g flour
- 300g caster sugar (divided into three: 150g + 100g + 50g)
- 3g of salt (1/2 teaspoon salt )
- 5 large eggs, separated
- 2 egg whites
- 2 tablespoons water
- 60ml of rapeseed oil
- 1 teaspoon vanilla extract
- 1 teaspoon cream of tartar
- 1 teaspoon lemon zest
- 1 tablespoon lemon juice
- 675g sugar
- 120ml strong coffee (two Nespresso capsules for me )
- 165g golden syrup
- 1 large pinch of salt
- 2¼ teaspoons baking soda
- 590ml of very cold doublel cream
- 2½ tablespoons sugar
- 2½ teaspoons vanilla extract
- 2½ tablespoons instant coffee granules
- Position a rack in the middle of you oven and preheat to 180°C. Line the bottom cake tin with a disk of parchment paper. Do not line the sides of the tin otherwise you chiffon cake will shrink when cooling down. Sift together the flour, 150g sugar and salt in a bowl.
- In the bowl of a stand mixer (or with an electric hand mixer), beat the egg yolks with 50g sugar at medium speed until the mixture thickens and becomes a pale yellow, about 4 minutes. Add the water, canola oil and vanilla and let the mixer run for a few more seconds until the mixture is homogeneous. If you use a stand mixer, transfer the mix into a big bowl, wash and dry the mixer bowl and whisk. If using an electric hand mixer, wash the whisks.
- Beat the egg whites. When frothy, add the cream of tartar and continue to beat. When the mixture begins to be firm, add the last 100g of sugar and beat until whites are firm and shiny. Without stopping the robot, add the zest and lemon juice. Mix for a few seconds until fully incorporated, stop the mixer.
- Using a spatula, stir the egg whites to the yolks mix. Then stir the powders in three times.
- Pour the mixture into the lined cake tin and smooth the batter with a spatula. Bake for 55 minutes to an hour until the top of the cake is golden and a toothpick inserted into the cake comes out clean. If your chiffron cake browns too quickly, you can cover it with aluminum foil. Let cool completely in pan. Once fully cooled down, remove from the tin, film and keep in fridge until you are ready to assemble your Blum's cake.
- Line a 33cm x 45cm x 2cm baking tray with of baking paper. Oil the baking paper with a brush.
- Equip a large saucepan (make sure to choose larger than small, the volume of the mix will triple once the baking soda is added) with a thermometer. Pour the sugar, coffee, golden syrup and salt in the saucepan and heat over medium heat until the mixture reaches 130°C, stirring occasionally with a heat resistant spatula.
- Meanwhile, measure baking soda and place it with a whip next to your hob.
- When your caramel reaches 130 ° C, increase to high heat and stir constantly, without forgetting the corners of the saucepan. When the mixture reaches 150°C, remove from heat and add the baking soda, whisking vigorously with the whisk. The mixture's volume will augment very quickly. Once the baking is incorporated, quickly pour the mixture onto the lined tray ( speed is the most important thing to obtain a beautiful honeycomp, using snapchat at same time is strongly discouraged - I speak of experiance ^^). Let the caramel cool for 30 minutes. Break the caramel into pieces with your hands or a knife. You can make the caramel in advance but beware of moisture, your caramel bites might stick to each other, even in an airtight container... I suggest you do the coffee crunch on the same day you eat the cake if you can.
- In a stand mixer, whip the cream, sugar, vanilla, and instant coffee together until firm.
- Cut the chiffon cake in half horizontally. Place the upper part, cut side up, on a turntable or cake stand. Cover with a layer of whipped cream, caramel bites and another of layer of whipped cream. Cover with the other half of the cake, cut side down. Cover the top and sides of cake with remaining whipped cream. Reserve in the fridge until serving.
- Before serving, cover cake with remaining caramel bites. If you add the caramel bites in advance, they begin to melt and lose their crunch... It is better to consume this Blum's coffee crunch cake the same day, but you can keep it in the refrigerator.