Preheat the oven to 350°F. Grease and line the bottoms of three 6-inch cake pans with parchment paper. Set aside.
Place the butter and chocolate in a heat-safe bowl set over a saucepan of simmering water. Cook until the butter and chocolate melt. Stir together and set aside to cool.
In a medium bowl, whisk together the Rodelle Gourmet Baking Cocoa, all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, whisk together the eggs and sugar until pale and frothy, 3 to 5 minutes. Add the vanilla extract and mix to combine. Pour in the cooled chocolate mixture and whisk until combined. Add the cocoa mixture. Use a rubber spatula to stir the batter together until there are no visible streaks of dry flour. A few lumps is okay.
Divide the batter evenly between the prepared pans. Bake for 30 to 40 minutes, or until a wooden skewer inserted into the center comes out with a few moist crumbs. Do no overbake.
Allow the brownie cakes to cool on a wire rack for 30 minutes. Once the pans are cool enough to handle, run a thin knife around the inner edge of the pan and unmold the cake layers. Allow the cake layers to completely cool.
For the Spiced Buttercream
Place the egg whites and sugar in the bowl of a stand mixer and whisk by hand until just combined. Fill a saucepan with a couple inches of water and bring to a simmer. Place the mixer bowl on top of the saucepan to create a double-boiler and reduce the heat to maintain a simmer (the water should not touch the bottom of the bowl).
Whisking intermittently, heat the egg white mixture until it reaches 160°F on a candy thermometer.
Carefully remove the bowl and place it on the stand mixer fitted with a whisk attachment. Whisk on high speed until stiff peaks form and the outside of the mixing bowl returns to room temperature, about 8 minutes.
With the mixer on low, add in the butter, a couple tablespoons at time. Once all of the butter has been added, stop the mixer and switch the whisk for the paddle attachment.
Mix the buttercream on medium speed until the butter is fully incorporated. Increase the speed to medium-high and mix until fluffy, about 5 minutes. Decrease the speed to low and add the Rodelle Vanilla Bean Paste, cinnamon, cardamom, and nutmeg. Mix on low until silky and smooth, about 2 minutes.
For the Caramel Sauce
Place the sugar, corn syrup, and water in a heavy-bottomed saucepan and gently swirl together to combine. Bring the sugar mixture to a boil over high heat, without stirring.
Cook until the bubbles begin to slow down and the sugar mixture turns a medium golden amber color.
Remove the caramel from the heat and very carefully whisk in the heavy cream. The mixture will bubble up and steam, so use caution.
Add in the butter, salt, and Rodelle Pure Vanilla Extract and mix until combined.
Transfer the caramel to a heat-safe jar or container and allow to cool at room temperature. The caramel will thicken as it cools.
To Assemble
Trim the tops of the brownie cake layers with a serrated knife until flat. Their centers will likely sink a little after the cool. Place one layer of cake on a cake board or serving plate. Spread about 1 cup of buttercream on top with an offset spatula until smooth.
Place the next layer of cake on top and repeat.
Use the remaining buttercream to frost the cake in a thin layer of icing. Pour the cooled caramel over the top of the cake and decorate as desired.
Note: This recipe was prepared for Rodelle by Tessa at Style Sweet.
