Smoky Salted Caramel-Chocolate Layer Cake Recipe
Makes one 7-inch cake
For the cakes:
For the smoky salted caramel:
For the buttercream:
First, make the cakes. Grease and line two 7-inch cake tins, and preheat the oven to 350°.
Place all the dry ingredients for the cake (everything from flour to salt) into a very large mixing bowl, and stir very vigorously with a whisk to get out any lumps out.
In a large measuring jug, whisk together the buttermilk, oil, eggs and vanilla, then stir into the dry ingredients. Finally, pour the hot water into the mix, and stir until everything is smooth and combined. The batter is fairly liquid-like thick custard.
Divide the batter evenly between the two cake tins, and bake for 35 to 40 minutes, or until the cakes springing back when touched in the center, and a skewer comes out with only a few moist crumbs. Place the cakes in their tins on a wire rack, and leave to cool completely.
Meanwhile, make the caramel. Place the water into a large, heavy based saucepan, and then pour the sugar into the center of the pan, making sure it is moistened by the water.
Place the pan over a medium-high heat, and cook without stirring until the sugar melts and begins to bubble. You can gently tip and swirl the pan if the sugar is not melting evenly. Continue to cook the sugar for about 5 to 8 minutes, or until it turns a dark golden amber color.
Remove the pan from the heat, and very carefully add in the butter and cream. The caramel will bubble up a lot, and hiss steam. But just carefully stir until everything melts and settles down.
Place the caramel back on the heat, just for 20 seconds or so, stirring to make sure everything is melted. Remove from the heat, add in the salt, and then pour into a jar or bowl and leave to cool completely.
To make the buttercream: Place the egg whites and sugar in a large bowl and stir with a whisk, just gently, to combine. Place the bowl over a pan of simmering water—the water should not touch the bowl—and whisk slowly until the mixture reaches 145°. If you don't have a thermometer, you can test by rubbing some of the mixture between your fingers. When you can't feel any sugar granules, and the mixture is hot (not boiling hot, just hot) to the touch, it's ready.
Remove the mixture from the heat and place into the bowl of a stand mixer fitted with the whisk attachment. Whisk the mixture at medium-high speed, until it triples in volume, becomes white and voluminous and cools down completely, about 7 to 10 minutes.
When the mixture is cool, begin adding the butter, about 1 tablespoon at a time, whisking for 20 seconds, or so, between pieces. Keep going until all the butter is in. At some point, the mix may begin to look soupy—don't worry, just keep whisking and I promise it will come together in a smooth, shiny frosting. Just keep whisking!
When all the butter is in, and you finally have a thick cloud of frosting, whisk in 1/2 cup of the cooled caramel. If the frosting is a little soft, chill it in the fridge for 15 to 20 minutes to firm it up.
To assemble the cake, trim the layers, if they are domed, and place one of the layers onto a cake stand. Top with half the buttercream and spread into an even layer right to the edge of the cake.
Top with the second layer and press down gently but firmly and evenly, sinking the cake into the frosting just slightly and making it bulge on the sides. Top with the remaining half of the frosting and, again, spread into an even layer right to the edge of the cake; let the buttercream overhang the edge a little bit, too.
Now, take a palette knife and smooth the frosting that is overhanging the layers all over and around the cake creating a very thin, smooth coating to cover the cake. Place the palette knife vertically against the edge of the top layer of frosting and smoothly drag it around the cake to create a flat wall of frosting. Then, working from the outside in, smooth out the top of the frosting to create a flat layer. Once the cake is coated, and everything is as straight and flat as you can get it, place the cake in the fridge to chill for at least half an hour.
When the cake is completely chilled, pour over about half a cup of the remaining caramel (you will have a little left over) and spread gently to the edge of the cake, allowing it to drip down the sides in a few places. Sprinkle a little extra salt on top, if desired, and serve!