Boston Cream Pie

Adjust rack to middle position and preheat oven to 350ºF (175ºC). Butter two 9-inch cake pans with unsalted butter, then dust with cake flour, shaking out excess.

In a medium bowl, whisk together cake flour, baking powder, and salt.

In a small saucepan, heat half-and-half and butter over medium-low heat until butter has melted, about 3 minutes.

In the bowl of a stand mixer fitted with the whisk attachment, whip eggs and granulated sugar on medium-high speed until yolks are thick and pale yellow color, and doubled in volume, 5 to 7 minutes.

Reduce mixer speed to low, and slowly pour in half-and-half mixture. Continue to whisk until combined, about 15 seconds.

With the mixer on low speed, gradually add the dry mixture 1/4 cup at a time, until just incorporated, about 2 minutes. Using a flexible spatula, scrape down sides and bottom of the bowl to ensure there are no dry bits. (If any remain, use spatula to gently fold until incorporated.) Divide batter between prepared cake pans and, using an offset spatula, smooth surface. Gently tap cake pans on kitchen counter to eliminate any large air bubbles.

Bake, rotating halfway through, until cake has risen by about 1 inch, is light golden, and springs back when gently touched, 17 to 20 minutes. Transfer pans to a wire rack and allow cakes to cool in pans for 30 minutes.

Run an offset spatula or butter knife around the edges of cake, then carefully invert cake onto a parchment-lined baking sheet. Let cool completely, at least 30 minutes. (Cooled cake can be lightly wrapped in plastic wrap and stored at room temperature for up to 24 hours.)

For the Simple Syrup: In a small saucepan, bring sugar and water to a simmer over medium heat and cook, whisking, until sugar is fully dissolved, 5 to 7 minutes.

For the Chocolate Ganache: Place chocolate, heavy cream, corn syrup, and salt in a medium heatproof bowl. Set over a small saucepan of gently simmering water and heat, stirring occasionally, until chocolate is fully melted, about 10 minutes. Remove from heat, stir to combine. Add butter and gently fold until ganache is smooth and shiny. Set aside until cool and slightly thickened (35ºC or 95ºF) but still fluid enough to pour, about 10 minutes.

To Assemble: Whisk pastry cream until smooth. Place one cake on a plate. Brush cake evenly with 1 to 2 tablespoons simple syrup. Top with 2 cups pastry cream, using an offset spatula to spread it evenly from edge to edge. Top with the second cake and brush cake evenly with 1 to 2 tablespoons simple syrup, allowing the cake to absorb it. Pour slightly thickened ganache over cake and, using an offset spatula, spread evenly to cover cake, letting excess ganache drip decoratively over the sides of the cake. Serve immediately or allow ganache to cool until firm.