Boston Cream Pie Recipe

Prep

Preheat oven to 350°F (175°C). Grease two 8-inch round cake pans and line the bottoms with parchment; grease parchment lightly and dust with a little flour, tapping out excess.

In a medium bowl whisk together flour, baking powder, and salt; set aside.

In a large bowl, beat the softened butter and granulated sugar together on medium-high speed until pale and fluffy, about 3–4 minutes.

Add eggs one at a time, beating briefly after each addition until incorporated; add vanilla with the last egg.

Reduce mixer to low and add about one-third of the dry ingredients, then half the milk, another third of dry, remaining milk, then remaining dry — mixing just until combined after each addition. Scrape bowl as needed; do not overmix.

Divide batter evenly between prepared pans (use scale or measure by eye). Smooth tops and bake on center rack 18–22 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs and cake springs back lightly. Rotate pans halfway through if your oven runs hot.

Let cakes cool in pans 10 minutes, then run a knife around edges and invert onto wire racks to cool completely. When cool, level domes with a serrated knife if necessary to make two even layers.

Place a medium heatproof bowl and whisk near the stove. If using a vanilla bean, split and scrape seeds; set pod and seeds aside.

In a medium saucepan, warm the 2 cups whole milk with the vanilla bean seeds and pod (or 1 tsp extract added later) over medium heat until just steaming and small bubbles form at the edges; do not boil. Remove from heat and set aside for 5 minutes to infuse if using bean.

In a bowl, whisk together the 0.5 cup sugar, egg yolks, cornstarch, and 0.25 tsp salt until pale and smooth.

Temper the yolk mixture: very slowly drizzle about 1/2 cup of the hot milk into the yolks while whisking constantly to raise their temperature. Then pour the tempered yolks back into the saucepan with the remaining milk, whisking constantly.

Return saucepan to medium heat and cook, whisking constantly, until mixture thickens and comes to a low boil — about 2–4 minutes. Boil gently for 30–60 seconds while whisking to cook out any starchy flavor; it should be very thick and glossy.

Remove from heat, whisk in the 2 tablespoons butter until smooth, then stir in vanilla extract if using instead of bean. Pour pastry cream into the prepared bowl and press plastic wrap directly on its surface to prevent a skin from forming. Chill in the refrigerator until completely cold, at least 2 hours (can be made a day ahead).

Before assembly, whisk the chilled pastry cream briefly to loosen it to a spreadable consistency. If too stiff, fold in 1–2 tablespoons milk to reach spreading texture.

Place chopped chocolate in a heatproof bowl.

In a small saucepan, heat the 1/2 cup heavy cream just until it begins to simmer (tiny bubbles at edges), then pour over the chopped chocolate. Let sit 1 minute, then whisk until smooth and glossy. Whisk in 1 tablespoon butter and 1 teaspoon corn syrup (if using) until incorporated.

Allow glaze to cool and thicken slightly (5–10 minutes) so it will pour but not run off completely.

Place one cake layer right-side up on a serving plate or cake board. If the top has a domed crust, place the cut/level side up so the smooth top is exposed for the filling (this makes assembly neater).

Spread the chilled pastry cream evenly over the first layer to within about 1/4 inch of the edge, smoothing with an offset spatula. Do not overfill; you want a single even layer of custard.

Carefully place the second cake layer on top, cut/level side down if you used that orientation previously, pressing gently so the edges of the cake meet.

Pour the chocolate glaze over the center of the top layer, using an offset spatula or the back of a spoon to coax it toward the edges so it covers the top and slightly drips over the sides. Work while the glaze is still pourable so it spreads smoothly. Catch drips on a plate or parchment underneath.

If desired, chill the assembled cake 15–30 minutes to set the glaze. Dust edges very lightly with powdered sugar if you like a contrasted finish (optional).

Slice with a sharp knife wiped between cuts for clean slices. Store refrigerated; pastry cream requires refrigeration. Best within 2–3 days.