For the chocolate cake:
¾ cup dark unsweetened cocoa powder, plus more for dusting
⅔ cup sour cream
1¼ cups hot water
2⅔ cups all-purpose flour
2 teaspoons baking powder
1 teaspoon baking soda
½ teaspoon salt
1½ sticks (¾ cup) unsalted butter, cut into cubes and softened
½ cup vegetable shortening
1½ cups granulated sugar
1 cup firmly packed brown sugar
3 large eggs, at room temperature
1 tablespoon pure vanilla extract
For the strawberry buttercream:
5 sticks butter, at room temperature
4½ cups confectioners’ sugar, sifted
1 1.2-ounce package freeze-dried strawberries
Pinch of salt
1½ tablespoons vanilla
¼ cup heavy cream
For the gold paint:
Gold luster dust
Vodka or lemon juice
I know not everyone will want to use the vegetable shortening called for in this recipe. I have not tried it for this cake, but as a general rule: If you want to swap in coconut oil, use an equal amount. If you want to use butter, you likely need to use 1.25 the amount.
To make the chocolate cake, heat the oven to 325º. Butter three 8-inch cake pans, line them with parchment and butter the parchment. Lightly dust the inside of the pans with cocoa powder and tap out the excess.
In a medium bowl, whisk together the cocoa powder, sour cream and hot water. Set aside to cool. Sift together the flour, baking soda, baking powder and salt into a large bowl and set aside.
Using a stand mixer fitted with the paddle attachment, combine the butter and shortening together on medium speed until light and fluffy, 3-5 minutes. Add the sugars and continue beating until light and fluffy, an additional 3-5 minutes. Add the eggs, one at a time, beating well after each addition. Scrape down the sides and bottom of the bowl as needed. Reduce speed to low and mix in the vanilla.
Add the flour mixture and cocoa mixture to the bowl in three alternating parts, beginning and ending with the dry ingredients. Mix until just incorporated. Scrape down the sides and bottom of the bowl, then divide the mixture evenly between the prepared pans. Use an offset spatula to smooth the top of the batter. Bake the cakes for 35-40 minutes, rotating the pans halfway through the baking time, until a toothpick inserted in the center comes out mostly clean. Transfer the pans to a wire rack to cool for about 30 minutes, then turn the cakes out onto the rack to cool completely.
If not frosting the same day, wrap well and place in the freezer. Take them out of the freezer about an hour before filing and frosting.
To make the frosting, pulse the freeze-dried strawberries in a spice grinder or food processor until powdery. It will be slightly under half a cup.
Place butter in the bowl of an electric mixer fitted with the whisk attachment. Whip on medium-high speed until smooth, about 1 minute. Add the confectioners’ sugar to the bowl and mix on medium-low speed just until incorporated. Add salt and freeze-dried fruit powder. Continue beating on medium-high speed until smooth, 1-2 minutes. Add the vanilla extract and heavy cream and beat on low speed just until incorporated. Increase the mixer speed to high and beat until light and fluffy, scraping down the bowl as needed, about 4 minutes.
To assemble the cake, place one of the cake layers on a cake board or serving platter. Spread an even layer of the frosting over the top of the cake, then top with the second cake layer. Repeat for the final layer of cake.
Frost the top and sides of the cake using a thin crumb coat, then place in the freezer for 10 minutes to set. Once the crumb coat is set, frost the top and sides of the cake again using an offset spatula. If painting with luster dust, place the frosted cake back in the freezer for another 10 minutes before painting.
If desired, paint the cake using luster dust. In a small bowl, combine luster dust and a few drops of vodka or lemon juice. Mix until it has a paint-like consistency; don’t get it too thin. Using a food-dedicated paint brush, lightly paint the sides and top of the frosted cake.
Cake can be kept at room temperature for a few hours. If making ahead of time, refrigerate in an airtight container and make sure to bring it to room temp before serving.