At a glance
Bake two 8-inch hot-milk sponge layers and fill them with chilled vanilla pastry cream. Chill the assembled cake, cut it into eight wedges, then spoon warm ganache over each slice. For an optional infused finish, measure the edible oil into the ganache for one plate.
Boston Cream Pie with Chocolate Ganache
Ingredients & directions
Hot-milk sponge, vanilla cream and ganache
Ingredients
Vanilla pastry cream
Hot-milk sponge
Ganache
Set out two 8-inch round pans, parchment, an electric mixer and a fine-mesh strainer. A cold filling is the difference between a clean layer and one that slides. Bake and cool the sponge while the pastry cream chills.
Directions
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Cook and chill the custard
Heat the milk for the pastry cream until it steams. Whisk the yolks, sugar, cornstarch and salt until smooth. Slowly whisk in half the hot milk, then return everything to the saucepan. Cook over medium heat, whisking, until thick bubbles break the surface. Whisk for 1 minute more. Strain into a shallow bowl, stir in the butter and vanilla, press food wrap onto the surface and refrigerate until cold, about 90 minutes.
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Bake the sponge layers
Heat the oven to 350°F (175°C). Grease and line the pans. Whisk the flour, baking powder and salt. Beat the eggs and sugar for 4 to 5 minutes until pale and thick enough to leave a brief ribbon. Fold in the dry mix in two additions. Warm the sponge milk and butter until the butter melts, stir in the vanilla, then whisk a ladleful of batter into the hot milk before folding that mixture back in. Divide between the pans and bake 22 to 27 minutes, until the centers spring back. Cool 10 minutes in the pans, then cool completely on a rack.
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Fill and settle the cake
Stir the chilled pastry cream just until spreadable. Place one sponge layer on a flat plate, spread the custard to within ½ inch of the edge, and set the second layer on top. Refrigerate about 1 hour so the custard firms up before you cut. Use a serrated knife and wipe it between slices.
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Glaze each slice
Heat the heavy cream until steaming. Pour over the chopped chocolate, wait 2 minutes, then stir until glossy. Cut the cake into 8 wedges and spoon a little ganache over each. If using the optional finish, stir the individually measured edible oil into the ganache for one wedge in its own cup, then transfer it to that identified plate.
Storage Cover and refrigerate the plain filled cake at 40°F (4°C) or below within 2 hours. Use within 3 days. Keep any infused topping separate and secured in a labeled container.
Kitchen notes
Get a clean custard layer
Why is it called pie?
Boston cream pie is a layer cake with pastry cream and chocolate. Massachusetts named it the official state dessert in 1996.
What if the custard looks loose?
Wait for bubbles to rise through the center before timing the last minute of whisking. The cornstarch thickens as it cooks and the cream firms further as it chills.
Can I make it the day before?
Bake and cool the layers and chill the pastry cream separately. Assemble the cake the next day, then spoon the ganache over each wedge when you serve.
Use the product label
Estimate THC in a portion
Measure only the edible oil stirred into the ganache for your slice. Use the same unit for the label amount and the amount used.
The result estimates the THC added to that portion from the product label. Keep infused portions labeled and secured.
THC in one portion = label THC (mg) × amount used ÷ label amount.
A label listing 4 mg THC per 1 mL gives an estimated 2 mg in one slice if you use 0.5 mL in its ganache.
Use a labeled edible product for a consenting legal-age adult where permitted. If you are new to edibles, Health Canada suggests choosing 2.5 mg THC or less. Full effects can take up to 4 hours. Keep infused servings separate, labeled and locked away from children and pets.