Step 1: Preparing & Baking the Cake
- 2 1/2 cup all-purpose flour
- 1 1/4 cup organic cane sugar, lightly ground
- 1 1/2 tsp baking powder
- 1 1/2tsp baking soda
- 1 1/4 tsp fine sea salt
- 9 tbsp (1/2 cup + 1 tbsp) neutral oil
- 1 1/2 cup + 3 tbsp non-dairy milk
- 3 tbsp pure vanilla extract
- 2 1/4 tsp apple cider vinegar
To start, position the oven rack in the middle of the oven and preheat the oven to 350°F (175°C). Oil the sides and bottom of 2-8"-inch cake pans and line the bottom with a parchment circle or cut the parchment paper to fit — do not oil the parchment afterward.
In a medium bowl, whisk, measure, and sift together the dry ingredients.
In a separate bowl or large measuring cup, add the oil, milk, vanilla, and vinegar and whisk until very well combined.
Next, pour the wet ingredients into the dry ingredients and whisk until the batter is smooth. Pour the batter into the prepared pans.
Transfer to the cakes to the preheated oven and bake for about 25 minutes or until the top has set, the sides have started to pull away from the pan and a tester or wooden toothpick inserted into the center comes out clean or with only a few moist crumbs attached.
Remove the cakes from the oven and place them on a wire cooling rack to cool for 10 minutes. Next, run a thin spatula around the sides of the cake to release the sides from the pan. Very carefully, invert each cake onto a wire cooling rack (1 cooling rack per cake) — then remove the pan and carefully peel off the parchment paper. Invert the cakes again so that the top is facing up on the rack. Cool completely.
When the cake is completely cool, slide a cardboard circle or a flat plate underneath it. Cover the cake tightly with plastic wrap and refrigerate until cold before glazing or frosting.
Step 2: Making the Pastry Cream
- 1 cup (5 oz) raw cashews, soaked for at least 4 hrs
- 1 cup canned full-fat unsweetened coconut milk
- 6 tbsp organic cane sugar
- 1 tbsp mild-tasting oil (such as olive oil, avocado or grapeseed oil)
- 1/4 tsp guar gum
- 1/8 tsp sea salt
- 3/8 tsp (just under 1/2 tsp) agar agar powder
- seeds from 1 vanilla bean
- 2 tsp pure vanilla extract
To make the pastry cream, first, rinse and then drain the cashews really well.
Next, using a high-speed mixer blend together the cashews, coconut milk, sugar, oil, guar gum, and salt. For the coconut milk, if you desire a really thick pastry cream (like for this cake), use just the thick coconut cream from the can. Start on low and then turn the speed up and blend until smooth.
Next, add the agar powder. Start the blender on low and then quickly increase the speed to high. Blend the mixture for approximately 2 minutes, or until the mixture gets really hot and starts to boil. If at any point the mixture stops moving and/or you hear the motor laboring use the tamper to move the pastry cream around.
Lastly, add the vanilla bean and vanilla extract and pulse a couple more times.
At this point, while the pastry cream is still hot, pour it into a container and cover just the surface with plastic wrap. Do not fully cover the pastry cream, you are merely trying to prevent a skin from forming. Cool the pastry cream to room temperature and then refrigerator for at least 4 hours, or even overnight. This pastry cream will keep for several days if covered and stored in the refrigerator.
Note that while this pastry cream is delicious in this Boston Cream Pie, it is also great in a variety of other desserts such as trifles and parfaits.
Step 3: Making the Ganache
- 1 cup + 2 tbsp non-dairy milk
- 4 tbsp corn syrup (or 1 to 2 tbsp mild tasting olive oil)
- pinch of sea salt
- 8 oz dark chocolate (70 to 72%), grated
- 1 tsp vanilla extract
To start the ganache, over medium-low heat, warm the non-dairy milk and corn syrup and salt in a small pot. Keep a close eye on it — you don’t want the milk to boil. Let the milk bubble slightly as this scorches the proteins, but stop it just before it boils. If it boils, the heat will destabilize the fat globules and it will split or separate the ganache.
Next, add the grated dark chocolate to milk and let sit for 30 seconds to give the chocolate time to melt into the hot milk. Grating the chocolate increases the surface area of the chocolate so that it melts into the milk faster.
Next, using a spoon, working from the center out, mix the chocolate into the milk to create an emulsion. As soon as the chocolate has melted into the cream and the mixture is smooth, glossy, and fully combined – STOP stirring. Lastly, stir in the vanilla and then set the ganache aside to cool at room temperature so it can set. It will firm up as it cools down. Do not stir or agitate the ganache while cooling; that can break it.
Allow the ganache to sit for approximately 15 to 20 minutes, or until it nicely coats a spoon with minimal dripping, but is still pourable.
Step 4: Assembling the Cake
To assemble the cake, simply place the first cake onto a cake pan, add the pastry cream, top with another layer of cake and then pour the ganache, starting from the center, over the cake, letting the ganache flow down the sides of the cake. See the above images for a visual guide of assembling the cake.
Place the cake into the refrigerator and let set for at least an hour or 2 before serving. If making several hours ahead of time, you may need to take the cake out and let it sit at room temperature before cutting it.
Chef's Notes
Boston cream pie was created by a French chef at the Parker House Hotel in Boston, Massachusetts, in the late 1800’s. The layers of the cake layers were originally soaked in rum, and the sides of the cake were garnished with toasted almonds but these days most folks just make it a bit more simple.
This version of Boston Cream Pie was inspired by Fran Costigan — the Queen of vegan desserts :)
One of the best things about this cake is that all of the components can be made ahead of time and because it’s so moist, it can even be assembled and kept in the refrigerator a day or two ahead of time.
The cake itself can be wrapped airtight in a double layer of plastic wrap and frozen for up to 2 months. When defrosting, be sure to defrost it unwrapped.
Also, note that this cake can be used to make a variety of different sized cakes and/or it can be used to make delicious cupcakes.
Extra Notes on Ganache:
The ratio here of chocolate to cream (in our case non-dairy milk), and the cocoa solid content in the chocolate are really important. Generally, a 1:1 ratio of chocolate to cream is used. There needs to be enough liquid (in the non-dairy milk) to suspend all the fat in the chocolate — 70% chocolate works well for this but keep in mind that the higher the cocoa solids and cocoa butter in the chocolate, the more non-dairy milk you will need, so if you use an 80% chocolate, you’ll need a ratio closer to 1:1.5 or 1:2. If there’s not enough liquid from the cream present, your ganache will be prone to splitting.
if the temperature of your ganache goes too high, it will cause the fat in the chocolate to separate. This will result in an oily/split/grainy ganache. The severity of the graininess will depend on how overheated your cream was.
If you let the ganache cool slightly and beat it with a whisk, you can create a light and fluffy texture perfect for cake fillings.