Ingredients:
For the Cake:
Room-temperature butter, for greasing the pans
2cups/260 grams cake flour
2¼cups/450 grams granulated sugar
2teaspoons Diamond Crystal kosher salt or 1 teaspoon Morton kosher salt
1½teaspoons baking soda
1½teaspoons baking powder
1cup/80 grams unsweetened Dutch-process cocoa powder, sifted if lumpy
¾cup/177 grams strong freshly brewed coffee, steaming hot
1cup/240 grams crème fraîche, at room temperature
1tablespoon vanilla extract
5large eggs plus 2 large yolks, at room temperature
¾cup/180 grams neutral oil, such as avocado or vegetable
For the Buttercream:
8ounces/226 grams semisweet chocolate (54 to 64 percent cacao), finely chopped
1cup/240 grams whole milk
½cup/100 grams granulated sugar
3tablespoons unsweetened Dutch-process cocoa powder, sifted if lumpy
2tablespoons all-purpose flour
1½teaspoons Diamond Crystal kosher salt or ¾ teaspoon Morton kosher salt
4large egg yolks
1¼cups/284 grams unsalted butter, cut into tablespoon-size pieces, at room temperature
2teaspoons vanilla extract
Directions:
For the Cake:
Step 1
Arrange an oven rack in the upper third of the oven and another in the lower third. Heat the oven to 350 degrees. Lightly coat the bottom and sides of 3 (8-inch) cake pans with butter, then line the bottoms with rounds of parchment paper and smooth the parchment to eliminate air bubbles.
Step 2
In the bowl of a stand mixer fitted with the paddle attachment, combine the cake flour, granulated sugar, salt, baking soda and baking powder; mix on low speed just until combined.
Step 3
Bloom the cocoa: In a medium bowl, whisk to combine the cocoa powder and hot coffee. Add the crème fraîche and vanilla, then whisk until completely smooth. Set aside.
Step 4
In a separate medium bowl, whisk the 5 whole eggs and 2 yolks until smooth; set aside.
Step 5
Mix the batter: To the stand mixer bowl, add the oil and half of the cocoa mixture; mix on low speed just until the flour is completely coated in the liquid ingredients. Pause the mixer and scrape down the sides and bottom of the bowl, then mix on medium until smooth and pasty, about 30 seconds. Pause and scrape down the sides and bottom of the bowl again, then add the whisked eggs and remaining cocoa mixture. Beat on medium speed, scraping down the sides and bottom of the bowl once or twice, until the batter is very silky and has the consistency of thin pancake batter, about 1 minute.
Step 6
Pour the batter into the prepared pans, dividing evenly. (For uniform layers, use a scale – you’ll get about 550 grams of batter per pan.) Transfer the pans to the oven, positioning two on the upper rack and one on the lower, staggering them so the pans above don’t block the one below. Bake, rotating the top two pans side to side and rack to rack after 20 minutes, until the tops of the cakes are domed, springy to the touch and a toothpick or cake tester inserted into the centers comes out clean, 25 to 30 minutes.
Step 7
Remove the pans from the oven and let cool completely on a wire rack.
For the Buttercream:
Step 8
To make the buttercream, start with the pudding base: Place the chocolate in the clean bowl of the stand mixer fitted with the paddle attachment. In a small saucepan, combine the milk and ¼ cup/50 grams of the sugar. Bring to a simmer over medium, stirring occasionally to dissolve the sugar, then remove from the heat and set aside. In a medium bowl, add the cocoa powder, flour, salt and remaining ¼ cup/50 grams sugar, and whisk until combined. Add the yolks to the bowl and whisk slowly to combine (it will seem very thick at first, but will loosen up), then whisk more vigorously until the mixture is pale, thick and smooth. Whisking the yolk mixture constantly, slowly stream in about half of the warm milk mixture, then whisk the contents of the bowl back into the saucepan. Set the saucepan over medium-low heat and cook, whisking constantly and scraping against the sides, until thick and bubbling, 1 to 3 minutes. Immediately scrape the pudding over the chocolate in the stand mixer bowl.
Step 9
Make the buttercream: Let the pudding mixture sit for a few minutes, so the heat gently melts the chocolate, then mix with the paddle on low speed until the chocolate is completely melted and the pudding is smooth and glossy. Increase the speed to medium and beat until the outside of the bowl is cool to the touch, 10 to 15 minutes. With the mixer running, add the butter a couple of pieces at a time, waiting for each addition to incorporate into the pudding before adding the next, until you have a smooth, glossy, spreadable frosting. Stop the mixer, thoroughly scrape the sides and bottom of the bowl, and add the vanilla. Beat once more just until evenly mixed.
Step 10
Unmold and level the cakes: Use a butter knife or small offset spatula to cut around the cooled cakes, pressing the blade firmly against the sides of the pans to loosen them. Invert the cakes onto a wire rack, remove the parchment paper if necessary, then invert again onto a second rack or cutting board so they’re domed side up. Holding a serrated knife parallel to the work surface, slice horizontally through the surface of each cake to level the layers. (The scraps are perfect for snacking.)
Step 11
Place one of the layers cut side-down on a serving plate, cake stand or cardboard cake round. Dollop about 1 cup buttercream in the center, then use an offset spatula to spread it evenly all the way to the edges. Place a second layer cut side-down over the first, center it, then top with another 1 cup of buttercream. Place the third layer on top, cut side-down, pressing gently to level it. Scrape about half of the remaining buttercream over the top of the cake, then use the spatula to spread it across the surface and down the sides, covering the entire cake in a very thin layer of frosting. (The cake will show through in several places; this is just the crumb coat.) Transfer the cake to the refrigerator and chill just until the frosting is firm, 10 to 15 minutes, then cover with the remaining frosting.
Step 12
The assembled cake will keep, loosely covered at room temperature, for 1 day. (Before covering the cake, chill it for 15 minutes so the frosting can firm up.) After 24 hours, refrigerate the cake and be sure to tightly cover any cut surfaces. Bring the cake to room temperature before serving.