Boston Cream Pie

Ingredients

• 2 cups whole milk
• 0.5 cups granulated sugar
• 5 large egg yolk
• 0.25 cups cornstarch
• 0.125 tsp salt
• 2 tsp vanilla extract
• 2 tbsp unsalted butter
• unsalted butter – to grease pan
• 1.25 cups all-purpose flour
• 1.5 tsp baking powder
• 0.5 tsp salt
• 4 large egg – at room temperature
• 1 cups granulated sugar
• 0.5 cups whole milk
• 4 tbsp unsalted butter
• 2 tsp vanilla extract
• 6 ounces semisweet chocolate – coarsely chopped
• 0.75 cups heavy cream
• 1 tbsp unsalted butter

Instructions

1. Make the pastry cream: In a medium bowl, whisk the egg yolks, granulated sugar (0.5 cup), and cornstarch until smooth and pale, 1–2 minutes.
2. Heat the whole milk (2 cups) in a saucepan over medium heat until steaming and small bubbles form at the edges; do not boil.
3. Slowly whisk the hot milk into the yolk mixture to temper. Return everything to the saucepan and cook over medium heat, whisking constantly, until thick and bubbling, 3–5 minutes; continue to whisk 1 minute after the first bubbles for a sturdy set.
4. Remove from heat and whisk in the salt (0.125 tsp), vanilla extract (2 tsp), and unsalted butter (2 tbsp) until glossy. Spread the pastry cream into a shallow dish, press plastic wrap directly onto the surface, and chill until cold and firm, at least 2 hours.
5. Prepare for the cake: Arrange an oven rack in the middle and heat the oven to 350°F (175°C). Grease a 9-inch round cake pan with unsalted butter (to grease pan) and line the bottom with parchment.
6. Whisk together the all-purpose flour, baking powder, and salt (0.5 tsp) in a medium bowl.
7. In a large bowl, beat the egg (4 large) and granulated sugar (1 cup) with a hand mixer or stand mixer on high speed until thick, pale, and tripled in volume, 4–6 minutes.
8. Warm the whole milk (0.5 cup) and unsalted butter (4 tbsp) in a small saucepan over low heat until the butter melts and the mixture is hot to the touch but not boiling, 2–3 minutes; remove from heat and stir in the vanilla extract (2 tsp).
9. Sift half of the dry ingredients over the egg mixture and gently fold just until incorporated. Fold in the remaining dry ingredients. Stream the hot milk–butter mixture around the bowl’s edge and fold gently until the batter is smooth and uniform.
10. Scrape the batter into the prepared pan and smooth the top. Bake until the cake is golden, springs back to a light touch, and a tester comes out clean, 25–30 minutes.
11. Cool the cake in the pan 15 minutes, then run a thin knife around the edge, invert onto a rack, peel off parchment, and cool completely, about 45 minutes.
12. Make the ganache: Place the semisweet chocolate (6 ounces) in a heatproof bowl. Heat the heavy cream (0.75 cup) in a small saucepan until steaming; pour over the chocolate, cover, and let stand 2 minutes. Add the unsalted butter (1 tbsp) and whisk gently until smooth and glossy. Let cool to a thick-but-pourable glaze, 10–15 minutes.
13. Assemble: Using a long serrated knife, split the cooled cake horizontally into two even layers. Place the bottom layer on a serving plate.
14. Whisk the chilled pastry cream to loosen, then spread it evenly over the bottom layer, leaving a 0.5-inch border. Place the top cake layer over the cream and press gently to level. Chill the stacked cake 20–30 minutes to set.
15. Pour the ganache onto the center of the cake and nudge it to the edges so it drips slightly down the sides. Let stand until the ganache is softly set, 20–30 minutes. Slice with a clean, warm knife and serve.