Boston Cream Pie Sheet Cake

Monday was Patriots’ Day. It’s a special day here in New England, a celebration of a truly unique nature. The day includes a day game at Fenway Park, the annual running of The Boston Marathon, and reenactments of the first battles of The Revolutionary War take place at sunrise on the Lexington Battle Green.

Schools and businesses are closed, people gather to enjoy the day’s fun and festive events. If we’re lucky, the sun shines and it feels like we’ve come to the end of another long winter. That’s a reason to celebrate all on its own.

But not this year. Sure, it was still Patriots’ Day. The date still marks the anniversary of the day in 1775 when the first shots of the Revolutionary War were fired.  But 2020 finds us in a place when there are no baseball games. It also brings us to an April where there will not be a marathon coursing through the streets of Boston. It’s a very different sort of Patriots’ Day, or just a Monday, for everyone.

Our family has its own Patriots’ Day tradition: I make a Boston Cream Pie. It’s a dessert all about Yankee ingenuity and it happens to be delicious. This year, I just didn’t feel like making our usual celebratory dessert. It takes several hours to make a traditional Boston Cream Pie from start to finish and I just didn’t have that in me.

While I didn’t want to spend all day making a cake, I sure did want to eat that delicious combination of sponge cake, pastry cream, and fudgy chocolate ganache. I also didn’t want to let a food tradition fall by the wayside.

So, I gathered up my recipe for traditional Boston Cream Pie and headed to the farmhouse kitchen.  I decided to bake this simpler cake in a glass casserole baking dish. I also decided that I wanted the cake to be delicious, but incredibly simple and quick to pull together. So, I made a few adjustments and set forth to create the cake with a bowl and a spoon, no mixer required.

The cake baked up beautifully. It had a nice, soft crumb with enough structure to stand up on its own. I added a thick layer of the pastry cream I usually make for Boston Cream Pie and then a fudgy layer of chocolate for good measure. While the shape was different and the effort had been considerably less, it sure looked like Boston Cream Pie to me.

Then came the moment of truth: it was time to serve up a square of this slightly different Boston Cream Pie to my family on the occasion of Patriots’ Day. I hoped that the first bite would bring them a bit of comfort, a brief moment of normalcy by marking the day with a family food tradition. I was filled with pride when it did. 

They were just as happy with this cake as the one I usually make. In fact, they remarked that it tasted just as delicious and that if a simpler recipe meant we could enjoy what had been a special occasion cake more often, they were thrilled. I was too.

Who knows what Patriots’ Day will look like next year? I won’t even hazard a guess. I will promise to keep baking, to keep serving comfort at our family table because it feels more important now than ever. Cake seems like a very good place to start.

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Boston Cream Pie Sheet Cake

Jennifer from 1840 Farm

This recipe is a simplified version of the traditional Boston Cream Pie that I make. They're equally delicious, but this version comes together quickly without the use of a mixer or the need to devote several hours of your day to the process. Instead, you can spend less time on the baking and more time enjoying the cake with someone you want to share it with.

Author: Jennifer from 1840 Farm

Ingredients

For the Vanilla Cake

• 4 large eggs
• 1 ¼ cup granulated sugar
• 1 teaspoon vanilla extract
• 2 cups All-purpose flour
• ¼ cup cornstarch
• 1 Tablespoon baking powder
• ½ teaspoon salt
• 1 cup whole milk or buttermilk (see substitutions below)
• 2 ounces oil (any neutral tasting oil will do. I like safflower.)

For the Pastry Cream

• 12 ounces whole milk
• 2 large eggs
• pinch salt
• ¼ cup All-purpose flour
• 6 Tablespoons granulated sugar
• 1 Tablespoon vanilla extract

For the Chocolate Fudge Topping

• 4 ounces heavy cream
• 2 cups chocolate chips or chopped chocolate

Instructions

For the Vanilla Cake

• Preheat the oven to 350° Fahrenheit. Position the oven racks in the top and bottom third of the oven. Prepare an oven safe 9×13 pan or casserole dish by coating with homemade magic pan release spread and sprinkling with granulated sugar. Set aside as you prepare the cake batter.
• I use whole milk, buttermilk, or whey leftover from making cheese or yogurt in this recipe. I use whatever I have on hand and need to find a use for. If you would like to use a buttermilk/whey substitute, you can measure out the cup of milk, remove one Tablespoon and replace it with a Tablespoon of white or apple cider vinegar. It will add the same tangy flavor to the cake as buttermilk or whey and the extra acidity will help the cake to rise.
• In a large mixing bowl, combine the eggs, sugar, and vanilla extract. Stir with a wooden spoon or spatula until the mixture is well combined.
• In a medium bowl, combine the flour, cornstarch, baking powder, and salt. I like to use a dry whisk to combine the dry ingredients and break apart any small lumps. You can sift them together if you prefer or skip the whisking/sifting entirely.
• Add the buttermilk (or whatever substitute you are using) and the oil to the mixing bowl with the sugar and eggs. Stir to combine. Add the dry ingredients to the bowl in one addition and stir until the mixture is smooth and well combined with no visible streaks of flour in the batter.
• Transfer the batter to the prepared baking pan. Transfer the pan to the preheated oven. Bake for 40-50 minutes, rotating halfway through the baking time. The cake is done when the top is lightly browned and a toothpick inserted into the middle of the cake comes out clean or with small crumbs attached.
• Remove the cake from the oven to a wire rack to cool slightly. While the cake is cooling, make the pastry cream.

For the Pastry Cream

• Place the whole milk in a medium saucepan. As the milk is warming, combine the eggs and dry ingredients in a medium bowl. Whisk to combine. The resulting batter should be thick and smooth.
• Move the pan of milk from the burner. Slowly add the egg mixture while whisking to incorporate the thick batter into the warm milk.
• Return the pan to medium low heat and bring to a simmer, whisking continuously until the mixture is thick enough to coat a spoon. Remove from the heat.
• Transfer the pastry cream from the pan (straining if necessary to remove lumps) to a bowl. Add the vanilla extract and whisk to combine. Allow the mixture to cool slightly until it is warm to the touch but not steaming hot.

For the Chocolate Fudge Topping

• Prepare the ganache by warming the heavy cream in a small pan or in the microwave in a microwave safe bowl for 30 seconds. Remove from the heat and add the chocolate. Allow the mixture to rest for two minutes before whisking to incorporate. When the cream and chocolate have become a thick, satiny mixture, it is ready.

To Assemble the Boston Cream Pie Sheet Cake

• Using the end of a wooden spoon or a chopstick, poke several holes in the surface of the warm cake. This will allow the pastry cream to be absorbed by the cake and create a delicious, moist cake and pastry cream combination. Pour the entire batch of pastry cream over the cake, spreading it evenly to fully cover the surface of the cake.
• Transfer all of the chocolate fudge topping to the pan. Spread the chocolate to fully cover the surface of the cake. If a bit of the pastry cream mixes with the chocolate, that's perfectly okay. It will still taste delicious.
• Transfer the fully assembled cake to the refrigerator. The cake can be kept in the refrigerator for several days, although it never lasts that long at our house!

Notes

This cake benefits from the use of cake flour. Due to food allergies, I struggled to find a brand of cake flour that was safe to use in our kitchen. Fortunately, I discovered that I could combine All-purpose flour and cornstarch to deliver the benefits of cake flour without adding allergens to our kitchen and one more specialty ingredient to our pantry. For each cup of cake flour called for in a recipe, simply weigh out one cup of All-purpose flour, remove 2 Tablespoons of the flour and add 2 Tablespoons of cornstarch.  You can learn more about this homemade substitute for cake flour and why it works here.

Tried this recipe?Mention @1840Farm or tag #1840FarmFood! We can’t wait to see what you make!