- ½ cup [120 g] sour cream (at room temperature)
- ½ cup [120 g] whole milk (at room temperature)
- ½ cup [112 g] canola oil
- 3 large eggs (at room temperature)
- 1 teaspoon pure vanilla extract
- 2 cups [284 g] all-purpose flour
- 1 cup [200 g] granulated sugar
- 1 cup [200 g] light brown sugar
- ¾ cup [75 g] VALRHONA COCOA POWDER
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 1 teaspoon salt
- 1 cup [240 g] hot coffee (strong)
- 2 [70 g] large egg whites
- ¼ teaspoon cream of tartar
- 2 tablespoons cold water, plus ¼ cup [60 g] room-temperature water
- 1 teaspoon gelatin
- ½ cup [168 g] corn syrup
- ½ cup [100 g] granulated sugar
- ¼ teaspoon salt
- 2 teaspoons pure vanilla extract
- 6 oz [170 g] Valrhona Equatoriale Dark (finely chopped)
- 1/3 cup [80 g] heavy cream
Toasted Graham Cracker Crumbs
- ½ cup [50 g] graham cracker crumbs
- 1 tablespoon granulated sugar
- 1 teaspoon unsalted butter (melted)
For the cake
- Adjust an oven rack to the middle position and preheat the oven to 350F [180C]. Grease three 6 by 2 in [15 by 5 cm] cake pans and line the bottoms with parchment paper.
- In a medium bowl or liquid measuring cup, combine the sour cream, milk, oil, eggs, and vanilla.
- In the bowl of a stand mixer fitted with a paddle, combine the flour, sugars, cocoa powder, and salt.
- With the mixer running on low speed, slowly add the milk mixture. Increase the speed to medium and beat until combined, 20 to 30 seconds. Slowly pour the hot coffee into the batter and mix until just combined. Using a spatula, give the batter a couple of turns to make sure it is fully mixed.
- Divide the batter evenly between the prepared pans. Bake for 25 to 35 minutes, until a wooden skewer or toothpick comes out with the tiniest bit of crumb.
- Transfer the cakes to a wire rack and let cool for 30 minutes. Turn the cakes out onto the rack, remove the parchment paper, and let cool completely. Once cool, the cakes can be frosted or wrapped in plastic wrap and refrigerated overnight.
For the marshmallow fluff
- In a small bowl, combine the cold water and the gelatin.
- In a medium, heavy-bottomed saucepan fitted with a candy thermometer, combine the corn syrup, sugar, room-temperature water, and salt. Bring to a boil over medium-high heat, until the temperature reaches 240 [120C]; this will take a few minutes. Immediately remove the saucepan from the heat, and whisk in the gelatin. Set aside while whisking the egg whites.
- In the bowl of a stand mixer fitted with a whisk, ship the egg whites and cream of tartar on medium-high speed until soft peaks form, 2 to 3 minutes.
- Turn the stand mixer to low speed, and carefully pour the hot sugar syrup along the side of the mixing bowl, being careful not to hit the whisk attachment as your pour (transferring the hot mixture to a liquid measuring cup with a pour spout might make this task easier). When all the syrup is in the bowl, turn up the speed to medium-high and continue whisking until the mixture has doubled in volume, is quite thick and glossy, and sides of the bowl have cooled, 8 to 10 minutes. Add the vanilla and mix until combined.
For the ganache
- Heat the cream.
- Gradually pour over the melted Valrhona Equatoriale Dark Chocolate.
- Mix using an immersion blender to create an emulsion.
- Cool to room temperature. When the ganache is cool, whisk for 30 to 45 seconds, until the ganache thickens a little bit. Let the ganache cool for ten minutes.
For the toasted graham cracker crumbs
- Adjust an oven rack to the middle of the oven. Preheat the oven to 325°F [165°C]. Line a baking sheet with parchment paper.
- Whisk together the graham cracker crumbs and sugar in a medium bowl. Add the melted butter and mix with a spatula until evenly incorporated. Spread the mixture on the prepared pan and toast in the oven until golden brown, 5 to 6 minutes.
Fill a pipping bag fit with a large round tip with the marshmallow fluff. Pipe a layer of marshmallow fluff over the top of each cake. Toast the marshmallow fluff with a kitchen torch. Chill the cakes in the fridge for 30 minutes while you make the ganache. Top the marshmallow fluff with the ganache, using an offset spatula to even the chocolate. Sprinkle the tops of the cake with the toasted graham cracker crumbs. Let the ganache set for 30 minutes. Wrap and give the cakes as gifts, or slice and serve.
Recipe courtesy of Sarah Kieffer, via Valrhona