Boston Cream Pie Recipe

Prepare and preheat

Preheat oven to 350°F (175°C). Grease and line two 8-inch (20 cm) round cake pans with parchment; grease parchment and lightly flour pans.

Combine dry ingredients

In a medium bowl whisk together 1.5 cups all-purpose flour, 1 cup granulated sugar, 1.5 tsp baking powder, and 1/4 tsp salt until evenly combined.

Mix wet ingredients

In a separate bowl or large measuring cup whisk 3 large eggs until lightly beaten. Add 1/2 cup whole milk, 1/4 cup melted cooled unsalted butter, and 1 tsp vanilla extract; whisk to combine.

Make batter

Pour the wet ingredients into the dry ingredients and fold gently until just combined and no dry streaks remain. Do not overmix; the batter should be smooth and slightly thick.

Bake

Divide batter evenly between the two prepared pans (use a scale or estimate). Smooth tops and bake in the center of the preheated oven 18–22 minutes, or until a toothpick inserted into the center comes out clean and cakes spring back lightly to the touch.

Cool

Allow cakes to cool in pans on a wire rack for 10 minutes. Run a knife around edges, invert onto racks, remove parchment, and cool completely. Once cooled, level tops if needed so layers are even.

Infuse milk

Split 1 vanilla bean and scrape seeds into 2 cups whole milk; add pod as well. In a medium saucepan, combine milk and vanilla pod and heat over medium until it just begins to steam and small bubbles form at the edge (do not boil). Remove from heat, cover, and let steep 10 minutes. If using vanilla extract, skip the steep: add 1 tsp extract later.

Whisk yolks and dry

In a medium bowl whisk 4 large egg yolks with 1/2 cup granulated sugar until pale and slightly thickened. Whisk in 1/4 cup cornstarch until smooth and free of lumps.

Temper and thicken

Remove vanilla pod from milk. Gradually pour about one-third of the hot milk into the egg yolk mixture while whisking constantly to temper. Then pour the tempered mixture back into the saucepan with the remaining milk, return to medium heat and cook, whisking constantly, until the mixture thickens and comes to a gentle boil (about 2–4 minutes). Continue cooking 30–60 seconds while stirring to cook out the cornstarch taste; it should be thick like pudding.

Finish pastry cream

Remove from heat and whisk in 2 tablespoons unsalted butter (and 1 tsp vanilla extract here if using extract instead of bean) until fully incorporated and glossy. Pour pastry cream into a shallow bowl or container and press plastic wrap directly onto the surface to prevent a skin from forming. Chill in the refrigerator until cold, at least 2 hours.

Heat cream

Place 4 oz chopped semisweet chocolate in a heatproof bowl. In a small saucepan, heat 1/2 cup heavy cream just until it begins to simmer and small bubbles appear at the edges (do not boil).

Make ganache

Pour the hot cream over the chopped chocolate and let sit 1 minute. Whisk gently from the center outward until smooth and glossy. Whisk in 1 tablespoon unsalted butter and 1 teaspoon light corn syrup (if using) until fully combined. Let the glaze cool slightly (5–10 minutes) so it thickens but remains pourable.

Layer and fill

Place one cooled cake layer on a serving plate or cake board. If the cake dome is pronounced, level it to make a flat surface. Spread the chilled pastry cream evenly over the top of the bottom layer, leaving about 1/4 inch from the edge to avoid spillover (you can pipe a small ring of pastry cream near the edge to help keep the glaze from running).

Top and chill

Carefully place the second cake layer on top, pressing lightly to adhere. Chill the assembled cake in the refrigerator 20–30 minutes to firm the pastry cream surface; this helps get a clean chocolate glaze finish.

Glaze the cake

Place the chilled cake on a wire rack set over a baking sheet to catch drips. Pour the warm (but not hot) chocolate glaze over the center of the cake and use an offset spatula to coax it gently toward the edges so it drips evenly down the sides. Work quickly—if glaze cools it will thicken and not spread smoothly.

Finish and serve

Let glaze set 15–20 minutes at room temperature or 10 minutes in the fridge. Optionally dust with 1 tablespoon confectioners' sugar before slicing. Slice with a sharp knife wiped between cuts for clean slices. Serve chilled or at cool room temperature.