Dark Chocolate Espresso Cake
Prep time: 
Total time: 
Intense coffee-soaked chocolate espresso cake layers filled with a dense, rich dark chocolate crémeux frosting and French coffee buttercream, finished with a bittersweet chocolate glaze and chocolate crémeux blobs. Serves 16-20.
For the chocolate espresso cake layers:
  • 255g (or 1 cup + 1 tablespoon) freshly brewed (hot!) coffee
  • 200g (or 1½ cup + 5 teaspoons) all-purpose flour
  • 150g (or 1¼ cup + 1½ teaspoon) Dutch-processed cocoa powder
  • 1½ teaspoons baking soda
  • ⅜ teaspoon baking powder
  • pinch of table salt
  • 1½ large eggs (about 84g or 3 ounces)
  • 110g (or 125ml, or ½ cup + 1 teaspoon) sunflower oil
  • 470g (or 2⅓ cup + 1 teaspoon) granulated sugar
  • 255g (or 1 cup + 1 tablespoon) buttermilk
  • ⅜ teaspoon vanilla extract
For the dark chocolate crémeux:
  • 325g (or 11.5 ounces) dark chocolate, 58% cocoa solids
  • 24g (or 5 teaspoons) unsalted butter
  • 230g (or 1 cup – 2 teaspoons) whole milk
  • 350g (or 1½ cup – 2 teaspoons) whipping cream
  • 9 large egg yolks (about 162g, or ½ cup + 2 tablespoons + 2½ teaspoons)
  • 75g (or ⅓ cup + 2 teaspoons) granulated sugar
  • 2¼ teaspoons cornstarch
For the coffee buttercream:
  • 3 large egg yolks (about 54g, or 3 tablespoons + 1 teaspoon)
  • 75g (or ⅓ cup + 2 teaspoons) granulated sugar
  • ¼ teaspoon vanilla extract
  • ¾ teaspoon instant coffee granules
  • 170g (or ¾ cup) unsalted butter, cubed and softened at room temperature
For the coffee soak:
  • 80g (or ⅓ cup) freshly-brewed coffee
  • 3 teaspoons granulated sugar
For the chocolate glaze:
  • 65g (or 2.3 ounces) dark chocolate, 63% cocoa solids
  • 75g (or ¼ cup + 1 tablespoon) whipping cream
  • 20g (or 1 tablespoon) honey
  • 25g (about 5 teaspoons) cold unsalted butter
Day 1: make the chocolate espresso cake layers:
  1. Preheat oven to 175°C/350°F (standard oven setting). Line the bottom of three 18-cm (7-inch) springform pans with baking parchment, butter the sides, and dust the sides with cocoa powder.
  2. Set aside the hot coffee, you’ll need it in a few moments and you want it to still be hot, but not scalding. In a large bowl, stir together flour, cocoa powder, baking soda, baking powder and salt. Set aside.
  3. In a large mixing bowl, mix together eggs, oil, and sugar until combined, 1 minute on high speed. Drizzle in the hot coffee, mixing as you go. The hot coffee will help dissolve the sugar, but you don’t want it scrambling the eggs. Once combined, add the buttermilk and vanilla and mix until combined, about 1 minute.
  4. Add the dry ingredients to the egg mixture. Using a rubber spatula, stir until mostly incorporated, then mix for about 30 seconds until the batter looks smooth (albeit grainy from the sugar).
  5. Divide the batter evenly over the prepared pans, then bake the cakes on a rack in the middle of the oven for 35-37 minutes, or until a tester inserted into the center of one of the cakes comes out with just a few moist crumbs attached. Remove the cakes from the oven and allow to cool to room temperature. Wrap tightly in plastic wrap and place in the fridge to chill overnight.
Day 1: proceed with the dark chocolate crémeux:
  1. Finely chop the chocolate and place in a large bowl with the butter. Set a strainer over the bowl and set aside.
  2. Combine milk and cream in a large, heavy-bottomed saucepan.
  3. In another large bowl, whisk together sugar and cornstarch. Add a splash of the milk mixture (about 5 tablespoons) and whisk until smooth. Add the egg yolks and whisk until foamy.
  4. Place the milk mixture (in the pan) over low heat, stirring with a spatula, and allow to just come to a simmer. Slowly drizzle the hot milk mixture into the egg mixture, whisking constantly to prevent the eggs from scrambling. Once all of the milk mixture has been added, pour the egg mixture back into the saucepan.
  5. Cook over low heat, stirring constantly with a spatula, until the mixture thickens and the bubbles disappear, and a thermometer inserted registers 82°C/180°F. Immediately remove from heat and pour into the strainer over the chocolate and butter in the bowl. Discard any curdled bits left in the strainer.
  6. Allow to sit for a minute, then stir the custard into the chocolate until the chocolate and butter have melted and the crémeux is an even color.
  7. Cover the surface of the crémeux with plastic wrap, pressing the plastic directly onto the surface of the crémeux with your hand, and refrigerate for one day to give the crémeux time to set up.
Day 2, make the coffee buttercream:
  1. Place the yolks in a medium-sized, heatproof bowl. Add the sugar and immediately whisk until foamy. Add the vanilla and coffee granules and whisk until combined. The coffee granules will dissolve later.
  2. Place the bowl over a pan of barely simmering water (making sure the water doesn't touch the bowl) and heat, stirring constantly with a rubber spatula, and scraping the sides and bottom of the bowl as you go, until the sugar has dissolved. You can check whether the sugar has dissolved by rubbing a bit of the mixture between your fingers.
  3. If you want to pasteurize the yolks and make the buttercream salmonella safe (I recommend doing this if you're planning on serving the buttercream to kids under the age of five, the elderly, pregnant women or people with ill health), gently heat the mixture to a temperature of 71°C/160°F. Use a digital sugar thermometer to monitor the temperature of the mixture. Once the mixture is hot enough, proceed with the recipe.
  4. Remove the bowl from the heat and mix (using a mixer fitted with the whisk attachment) until the mixture thickens and drops in ribbons when you lift the beaters, and has cooled completely to room temperature. Fun fact: you have now made pâte à bombe! Aren’t you fancy ;)
  5. Transfer the pâte à bombe to another bowl and add the butter to the mixing bowl of your mixer. Using the paddle attachment, beat the butter until light and fluffy, about 5 minutes on high speed, scraping the sides and bottom of the bowl with a rubber spatula when necessary.
  6. Once the butter is fluffy, add the pâte à bombe one tablespoonful at a time, mixing well after each addition. Once you’ve added all the pâte à bombe, mix for another 2 minutes until the buttercream is smooth and fluffy.
  7. Buttercream can be stored, covered tightly with plastic wrap, in the fridge for up to 1 week, but I personally think it’s easiest to just use it fresh. To use buttercream that has been chilled, allow it to come to room temperature first, then mix until soft and spreadable again. If the buttercream separates, just keep mixing. Mix long enough and it WILL come together!
In the meantime, make the coffee soak:
  1. Combine hot coffee and sugar in a mug. Stir to combine and allow the soak to cool to room temperature.
  2. Use half of the soak to moisten one 18-cm/7-inch cake layer. Top the cake layer with a filling of choice, and place another cake layer on top, pressing down gently.
  3. Use the remaining soak to moisten this second cake layer. Again, fill with your favorite filling, and top with a third cake layer. Frost the cake with a frosting of choice and decorate.
  4. The soak is best made right before you need it.
Assemble the cake:
  1. Place first cake layer onto a serving plate. Drizzle with 2 tablespoons of coffee soak. Top with 180g (¾ cup) of dark chocolate crémeux, spreading it evenly over the cake layer using an offset spatula. Top with 130g of the coffee buttercream (another ¾ cup, or half the batch). Gently spread the buttercream evenly over the layer of crémeux.
  2. Top with second cake layer, pressing it down lightly to make sure it sticks. Drizzle with another 3 tablespoons of the coffee soak, then frost with 180g (¾ cup) of chocolate crémeux and 130g (¾ cup, or the remaining half of the batch) of coffee buttercream. Top with the final cake layer.
  3. Reserve about half a cup of the chocolate crémeux, then frost the entire cake with a thick layer of the remaining crémeux. Use a bench scraper to smooth the top and sides of the cake. Place the cake in the fridge to chill thoroughly for at least 1 hour.
Right before taking the cake out of the fridge, make the glaze:
  1. Finely chop the chocolate and place it in a medium-sized, heatproof bowl set over a pan of simmering water to melt.
  2. Once the chocolate is almost completely melted, combine cream and honey in a small saucepan and heat gently, stirring occasionally, until it has reached scalding point. Slowly pour the hot cream mixture into the melted chocolate, stirring with a rubber spatula until smooth. Remove from heat.
  3. Add the cubes of cold butter and stir until completely melted and the chocolate glaze looks smooth and shiny. If necessary, allow to cool to dripping consistency (thickness of melted chocolate) or, if the glaze has cooled too fast, place bowl back over the pan of simmering water and heat it to dripping consistency (thickness of melted chocolate).
  4. Remove the cake from the fridge and use a teaspoon to pour small amounts of glaze near the edges of the cake so that it drips down the sides of the cake. Pour some glaze on top of the cake and spread evenly using an offset spatula or the back of a spoon. You might have some leftover glaze. Place the cake in the fridge to allow the glaze to set.
  5. Fit a piping bag with a large open tip and fill with the reserved crémeux. Pipe simple dollops of crémeux around the edge of the cake.
  6. Cake keeps for a couple of days, stored in an airtight container in the fridge. Allow to come to room temperature before serving.
Recipe by The Tough Cookie at https://thetoughcookie.com/2017/04/26/mock-version-of-proof-bakerys-chocolate-espresso-cake/