Ingredients
Method
Preheat oven to 350°F (175°C). Line bottoms of two 9-inch round cake pans with parchment paper greased with nonstick baking spray, but leave the sides of the pans untouched. The cakes need to cling to the ungreased pans to rise properly.
In a large bowl, whisk together 2 cups plus 1 Tbsp. (230g) cake flour, 2 tsp. baking powder, and ½ tsp. Diamond Crystal or ¼ tsp. Plus ⅛ tsp. Morton kosher salt and then sift back into the bowl. Set aside.
In a stand mixer fitted with the whisk attachment, whip 3 large eggs, at room temperature, and 2 large egg yolks, at room temperature, on high speed. Once the eggs are well combined and starting to foam, about 1 minute, turn the speed to medium-low and sprinkle ¾ cup (150 g) granulated sugar slowly over top. Turn the speed to high and let it whip for about 5 minutes.
While the eggs are whipping, in a small saucepan over medium heat, bring ¾ cup (175ml) whole milk, 2 Tbsp. mild-flavored oil (such as vegetable oil), and remaining ¾ cup (150g) granulated sugar to a boil. Turn off the heat and stir in 1 Tbsp. vanilla extract.
Once the eggs are light in color and thick, they should be able to form a ribbon of batter that sits on top of the egg foam for a few seconds when you lift the whisk out of the foam. Turn the mixer speed to low, slowly add the boiling milk mixture, and then add the flour mixture, a few tablespoons at a time, scraping down the bowl several times.
Immediately pour the batter into the prepared pans and gently run a spatula through the batter to pop any large air bubbles.
Bake until a tester comes out clean, 15–20 minutes. Let the cake cool completely in the pans. Run a knife around the edge before turning out onto serving plates.
In a medium saucepan over medium heat, combine 2 cups (480ml) whole milk, ¼ cup (50g) granulated sugar, ¼ cup (55g) unsalted butter, 1 pinch kosher salt, and the seeds scraped from ½ vanilla bean (or 2 tsp. vanilla extract); bring to a gentle boil; and then remove from the heat.
In a medium bowl, whisk together 3 Tbsp. cornstarch and the remaining ¼ cup (50g) granulated sugar. Add 1 large egg, at room temperature, and 4 large egg yolks, at room temperature, and whisk into a smooth paste.
Whisk enough of the hot milk, a little at a time, into the egg mixture until it is warm to the touch. Once the eggs are tempered, pour the mixture back into the remaining milk in the pan.
Return the saucepan to medium-high heat and bring the mixture to a boil; continuously whisk for 3 minutes more or the pastry cream will separate once it cools.
If there are any lumps in the pastry cream, strain it through a fine-mesh sieve into a shallow container and cover with plastic wrap, pressed directly onto the surface, to prevent a skin from forming.
In a large bowl, add enough ice cubes and cold water to create a bath for the container to sit in without the water breaching the sides.
Set the container in the ice bath or place in the freezer until chilled, about 15 minutes before using. Or transfer to an airtight container and store in the refrigerator for up to 3 days.
In a medium saucepan over low heat, warm 2 cups (480ml) heavy whipping cream until just simmering. Turn off the heat and add 16 oz. (450g) bittersweet chocolate, finely chopped. Swirl the pan to make sure all of the chocolate is submerged in the hot cream. Let sit for 3 minutes and then gently stir until smooth. Do Ahead: Store ganache in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 1 week. Gently warm the ganache over a pan of simmering water, forming a double boiler, to a pourable or spreadable consistency, depending on your needs.
Place one cake layer on a serving plate.
Stir the pastry cream to loosen. In a medium bowl, whip remaining ⅓ cup (80ml) heavy whipping cream to stiff peaks. Fold ⅓ of the whipped cream into the pastry cream to lighten, then fold in the remaining whipped cream.
Using an offset spatula, spread all of the pastry cream over the cake; making sure not to go quite to the edge. Place the second cake layer over the pastry cream. Gently press down on the cake to make sure it is sitting snugly on the pastry cream. If the pastry cream goes beyond the edge, clean it up with a metal decorating spatula. Cover with plastic wrap and refrigerate for about 1 hour to set the pastry cream in place.
Pour the ganache over the top of the cake, starting in the center and stopping just as it drips over the edge.
Refrigerate the cake until the ganache sets, about 30 minutes, then serve right away.