Chocolate Peanut Butter Cake (with Caramel Peanut Butter Nougat Filling and Chocolate French Buttercream Frosting)

Chocolate cake

1. Preheat the oven to 180°C / 350°F. Butter and line two, 8 inch cake pans with parchment paper (if you're not using parchment paper, butter and flour the two pans).
2. Sift all the dry ingredients in a large bowl or your mixing bowl (if you’re using a stand mixer).
3. In a large jug (pitcher) or smaller bowl, whisk the eggs, buttermilk, oil and vanilla until just mixed. Add this liquid mix into the dry ingredients slowly while mixing it with your stand mixer (or whisk by hand or hand-mixer). Make sure the batter is smooth and thick without any lumps.
4. Pour the freshly brewed coffee into the batter while mixing. The batter will become very thin, so be careful as the batter might splash if the beater is too fast. Mix only until everything is well combined. Divide batter between the two pans.
5. Bake the cakes in the preheated oven for about 30 - 40 minutes, rotating them once around the 20 minute mark. The cake is done when a toothpick inserted into the cake comes out with only a few cake crumbs on it (i.e. not completely clean).
6. Cool the cakes in the pan for about 15 minutes, and then turn out onto cooling racks carefully (the cake is really soft) to completely cool.

Peanut dacquoise

1. In a food processor, combine the roasted, salted peanuts, cornstarch, and 1.4 oz / 40 g of the sugar. Process until the peanuts have been finely processed.
2. Draw two 8 inch circles on parchment paper. Turn the paper over and make sure these circles fit within the width of your baking sheet. Preheat the oven to 250°F / 120°C.
3. In a clean, dry mixer bowl (of your stand mixer or hand mixer) whisk the egg whites with the cream of tartar using a whisk attachment, until it gets frothy.
4. Gradually add the sugar while whisking well, making sure to incorporate the sugar well into the egg whites. Keep whisking until the egg whites become thick and glossy and reach the stiff peak stage.
5. Fold in the ground peanuts in 2 additions, being careful not to deflate the egg mixture.
6. Divide the mixture equally between the two circles and spread it evenly inside the drawn line.
7. Bake in a preheated oven for 1 ½ hours, rotating only once inside the oven (take care not to keep the oven door open for long). Turn off the oven and let the dacquoise cool completely in the oven (about 1 - 1 ½ hours)

Salted caramel buttercream frosting

1. In a saucepan, add the sugar and melt over medium high heat. Stir the sugar with a clean, dry silicone spatula to evenly melt the sugar. 
2. The sugar will melt first and then start to caramelize. Stir the mixture so that the sugar melts well and caramelizes evenly.
3. Allow the caramel to turn amber in color. Lower the heat to low and remove the pot from the heat.
4. Immediately add the warm cream. (Be careful here as this will generate a lot of steam and could potentially burn your hands!)
5. Place the pot on low heat and stir until the caramel is dissolved in the cream and is smooth. Remove the pot from the heat and turn off the stove.
6. Allow the caramel to cool to slightly warmer than room temperature. The caramel should still have some flow to it.
7. In a mixer bowl, add the cool butter and the slightly warm caramel, and salt. With a whisk attachment, cream the butter on high speed until the butter is light and fluffy.
8. Add the confectioner's sugar in batches and whisk on medium speed. First add half of the confectioner's sugar and mix until the frosting is creamy. Then add the other half if you'd like a stiffer buttercream.
9. The icing can be refrigerated. However, let it soften to room temperature and whisk it before using it.

Salted caramel and peanut nougat filling

1. Prepare the salted caramel frosting as above, and set it aside.
2. In a pan, combine the butter, sugar, evaporated milk, and heat on low, stirring occasionally until the sugar dissolves and the mix comes to a boil.
3. Boil this mixture for about 1 - 2 minutes. Then remove from the heat and stir to make sure it's smooth. Add the peanut butter and marshmallow fluff, and whisk until well incorporated. Let it cool to room temperature.
4. Add cold whipping cream and whisk with a hand-held beater for about 2 minutes until smooth. Set aside.

Chocolate French buttercream frosting

1. Place the egg yolks in a heat-proof bowl, together with the sugar. Whisk until it becomes frothy. Add vanilla and salt, and keep whisking until egg yolks become pale and foamy and the sugar has almost completely dissolved.
2. Place the bowl with the yolk and sugar mix over a pan of simmering water (without the bowl touching the water), and whisk constantly while gently heating the mix to a temperature of 150°F / 65°C. Please see recipe note below on how to pasteurize the egg yolk and sugar mix.
3. Remove from the heat and whip the egg yolk until the mix thickens and reaches the ribbon stage. Make sure you keep mixing until it has cooled to room temperature.
4. Add butter, 1 tablespoon at a time, incorporating each piece of butter well before adding the next one. Keep adding the butter until the buttercream is nice and fluffy. I add 9 oz / 250 g first and only add the rest if the buttercream isn’t fluffy enough.
5. Add the melted and cooled bittersweet chocolate and incorporate it into the buttercream with the mixer.

Assembly

1. First take one chocolate cake layer. Spread half of the peanut butter nougat layer on top of it. Spread half of the salted buttercream frosting on top of the nougat layer. Next layer is the dacquoise. Then the rest of the nougat and rest of the caramel frosting.
2. Top with the second layer of chocolate cake.
3. Frost the cake with the chocolate French buttercream.
4. Decorate with peanut brittle if you like, or any way you prefer!