Adapated from Baked Explorations’ Aunt Sassy Cake
Ingredients for the cake:
1 cup shelled pistachios (plus 1/3 cup for decorating)
2 1/2 cups cake flour
3/4 cup all-purpose flour
1 tablespoon baking powder
1 teaspoon baking soda
3/4 teaspoon salt
1/2 cup (1 stick) unsalted butter, softened
1/2 cup vegetable shortening
1 3/4 cups sugar
1 tablespoon pure vanilla extract
1 large egg
3 large egg whites, at room temperature
1 1/2 cups ice-cold water
1/4 tsp cream of tartar
Ingredients for the Honey Vanilla Buttercream:
1 1/2 cups sugar
1/3 cup all-purpose flour
1 1/2 cups whole milk
1/3 cup heavy cream
1 1/2 cups (3 sticks) unsalted butter, soft but cool, cut into small pieces
1 teaspoon pure vanilla extract
3 tablespoon honey
Make the cake:
Preheat the oven to 325° F. Butter three 8-inch round cake pans, line the bottoms with parchment paper and butter the parchment. Dust parchment with flour and knock out excess flour.
In the bowl of food processor, pulse the pistachios until they are coarsely chopped. Transfer about 2 tablespoons’ worth of the coarse pistachios to a large bowl. Continue to process the rest of the pistachios until they are almost powdery, but not a superfine dust. Stir the pistachio powder into the reserved coarse pistachios. Sift the flours, baking powder, baking soda and salt, together over the large bowl containing the pistachios mix. Stir to combine.
In the bowl of a standing mixer fitted with the paddle attachment, beat the butter and shortening on medium speed until creamy, 3 to 4 minutes. Add the sugar and vanilla and beat until fluffy, about 3 minutes. Scrape down the bowl, add the whole egg, and beat until just combined. Turn the mixture to low.
In a measuring cup, make 1 1/2 cups ice water. Add the flour mixture to the mixer in three parts, alternating with the ice water, beginning and ending with the flour mixture. For each addition, turn the mixer to low to add ingredients, then up to medium speed for a few seconds until incorporated. Scrape down the bowl, then mix on low-speed for a few more seconds.
In a medium bowl, whisk the egg whites and cream of tartar until soft peaks form (You can do this by hand. Don’t be intimidated, it should only take 2 to 3 minutes). Do not over beat. Gently fold the egg whites into the batter.
Divide the batter among the prepared pans and smooth the tops. Bake for 40-45 minutes, rotating the pans halfway through the baking time, until a toothpick inserted into the center of the cake comes out clean. Transfer the pans to a wire rack and let cool for 20 minutes. Turn the cakes out onto the rack and let cool completely. Remove the parchment paper.
Make the honey vanilla buttercream:
In a medium heavy-bottomed saucepan, whisk the sugar and flour together. Add milk and cream and cook over medium heat whisking occasionally, until the mixture comes to a boil and has thickened, about 10 to 15 minutes.
Transfer the mixture to the bowl of a standing mixer with paddle attachment. Beat on high until cool (this takes at least 7 to 9 minutes of mixing) then add the butter; mix until thoroughly incorporated. Increase the speed to medium-high and beat until frosting is light and fluffy, 1 to 2 minutes.
Add the vanilla and honey and continue mixing until combined. If the frosting is too soft, put the bowl in the refrigerator to chill slightly, then beat again until it is proper consistency. If the frosting is too firm, set the bow over a pot of simmering water and beat with a wooden spoon until it is the proper consistency.
Assemble the cake:
Place one cake layer on a serving platter. Trim the top to create a flat surface, and evenly spread about 1 1/4 cups frosting on top. Add the next layer, trim and frost it, then add the third layer. Spread a very thin layer of frosting over the sides and top of the cake and put it in the refrigerator for bout 15 minutes to firm up. (This is known as the crumb coating and will help keep loose cake crumbs under control when you frost the outside of the cake.) Spread the sides and top of the cake with the remaining frosting. Garnish the cake with crushed pistachios and refrigerate it for 15 minutes to it firm up before serving.
This cake will keep beautifully in a cake saver at room temperature for up to 3 days, if the weather is humidity free. Otherwise, put it in a cake saver and refrigerate it for up to 3 days. Let the cake sit a room temperature for at least 2 hours before serving.