Boston Cream Pie

I don’t remember the first time I tried Boston cream pie. I do, however, remember my confusion before trying it for the first time: Wait, it’s not a pie? The dessert’s name had bamboozled me, like it had many others. I was, until I ate it for the first time, under the impression that a dessert called Boston cream pie was, in fact, a pie. Imagine my surprise when someone served me a layer cake with lush vanilla pastry cream sandwiched between two soft sponge cakes and a thin coating of rich chocolate ganache on top. Though it was nothing like the cream pie I’d envisioned, it was delicious. There’s not much to hate about cake, pastry cream, and chocolate—and polishing it off was as easy as pie.

The Origins of Boston Cream Pie

Today, Boston cream pie is the official dessert of Massachusetts, but where it comes from is often disputed. Some say the cake is a custard-filled variation of Washington pie, a jam-filled layer cake that was popular in the 1800s. Others credit Boston’s Parker House hotel (today the Omni Parker House) with inventing it. According to Greg Patent, a James Beard award–winning cookbook author who traced the origins of the dessert for Gastronomica, it’s possible that both theories are true: That bakers did make versions of the Washington Pie with custard and that, separately, the hotel came up with what they thought was an original dessert. 

Many recipes for Washington pie in the late 1800s gave home cooks the option of using pastry cream or custard, but with no mention of the BCP’s signature chocolate glaze. Cookbooks from that era, like Fannie Farmer’s 1895 The Boston Cooking-school Cook Book, include recipes for similar desserts—custard-filled or cream-filled cake, albeit without the chocolate glaze—under different names, like cream pie, French cream cake, or Boston cream cake. This suggests that home cooks were making some version of “Boston cream pie” despite there not being a common name for the sweet.  

The Omni Parker House’s archival material, including menus and recipe books, suggest they were the first to serve the dessert as we know it today: a tender cake called a biscuit au beurre split in two, layered with pastry cream, and glazed with chocolate. Writing for GastroObscura, journalist Julie Tremaine says it was the Boston cream pie that changed how most Americans approached chocolate as an ingredient. At the time, chocolate wasn’t a widely available ingredient. Before the BCP, most Americans enjoyed chocolate as a drink; using chocolate in a cake was “groundbreaking.” The dessert, Tremaine says, “was a pioneer, forever changing Americans’ relationship with chocolate.”

As chocolate became more common, American home cooks sought to recreate the famous dessert at home. “Thus, what we call the Boston Cream Pie today is an attempt to copy a glorious hotel dessert…which evolved separately from the Washington Pie,” Patent writes. As to why the confection is called a pie, bakers originally prepared Boston cream pie in Washington pie plates. Though we no longer bake the sponge in a pie tin, the dessert’s name remains.

An Easier Approach to Biscuit au Beurre: Hot Milk Cake

The pastry chefs at the Omni Parker House make their BCP with a biscuit au beurre, a tender French cake. Like the genoise, there are no chemical leaveners in a biscuit au beurre; it instead relies entirely on whipped eggs for its light and fluffy texture. Making the cake successfully involves whipping the egg whites and yolks separately with sugar until doubled in volume, gently folding flour in, followed by melted butter. Though the method itself seems pretty straightforward, several complications can arise: you could under or over whip your egg whites or deflate the batter while incorporating the flour, threatening the cake’s ability to rise in the oven.

You don’t have to go through all that trouble for a cake with a similar texture, though. In this recipe, I’ve opted for a much simpler sponge that’s practically impossible to mess up—and still bakes into a light, golden cake with a texture close to that of biscuit au beurre. And you don’t even have to separate the eggs! Allow me to introduce you to hot milk cake, a dessert that dates back to the early 1900s and became especially popular around the Depression and World War Two.

Home cooks loved it for its versatility and affordability; when ingredients like fresh dairy and sugar were rationed during wartime, American home cooks relied on pantry staples like milk powder. Many hot milk sponge cake recipes from that era had bakers use non-fat dry milk powder in place of fresh milk, making the confection even more affordable and accessible. Many newspapers from that era, including the St. Louis Star-Times in 1948, described the cake as “inexpensive and easy to make.”

“Every homemaker likes to have a quick, easy, good-tasting cake recipe that can be whipped up for unexpected company or family desserts,” wrote Marian Manners in The Los Angeles Times in 1952. “The hot milk sponge cake…is just that exact cake.” To make the cake, all you had to do was whip whole eggs with sugar until pale, fluffy, and doubled in volume, then pour in a mixture of hot milk and butter, before finally incorporating the flour, salt, and baking powder. Everything comes together in the bowl of a stand mixer—no gentle folding of whipped egg yolks into egg whites followed by flour and butter.

Like the biscuit au beurre, the aeration from whipping eggs helps leaven the cake. But unlike its French cousin, the hot milk sponge cake has baking powder, which offers an additional layer of protection and guarantees its rise. While the biscuit au beurre only calls for melted butter, hot milk cake typically involves a mixture of hot milk and butter. In both cakes, the melted fat coats the flour particles, making it more difficult for gluten chains to develop and producing a soft cake. 

While whole milk did produce a pillowy cake, I wanted to up the fat slightly for a more tender crumb—and landed on a mixture of half-and-half with butter in this recipe. Heavy cream made the cake heavier than ideal, but half-and-half struck a happy medium. I also experimented with vegetable oil—which is 100% fat—in place of butter, but the cake lacked the rich flavor that butter brought, and there wasn’t a particularly noticeable difference in tenderness. Like the biscuit au beurre, the hot milk sponge is tender and flavorful.

The Pastry Cream

Pastry cream, or crème pâtissière, stars in many popular desserts, including éclairs and cream puffs and…wouldn’t you know it, Boston cream pie. We could go the easy way out and use instant custard or pudding mix, but most ready-made mixes are cloyingly sweet, with an artificial flavor that I generally find unpleasant. Whipping up your own pastry cream allows you to control the sweetness and thickness of the filling, and if you have time to spare, you could even infuse the milk overnight with a vanilla bean.

Below, I use former editor Kristina Razon’s tried-and-true method for pastry cream. Steeping the milk with a scraped vanilla bean infuses it with a deep, floral flavor, while cornstarch helps to thicken it. The secret to pastry cream success is to cook the custard adequately on the stove by allowing it to bubble for a full minute. This allows the cornstarch to gelatinize—thickening the custard—and deactivates amylase, an enzyme that can slowly eat away starch molecules and turn pastry cream into a watery mess. Don’t worry about curdling the cream; as Kristina notes, “the milk dilutes the egg proteins, so they’re farther apart and less likely to rapidly and tightly bond. On top of that, both the starch and the sugar run additional interference to prevent the egg proteins from bonding.” So let your pastry cream bubble away—just make sure you’re whisking constantly to prevent scorching.

The Simple Syrup

If you’ve ever had a bad layer cake, chances are it was appallingly dry. While the Boston cream pie is made with a soft hot milk cake and has plenty of velvety pastry cream, it doesn’t hurt to quickly brush the cake with some simple syrup to keep it moist. It’s the easiest thing to do: combine sugar and water together in a saucepan over medium heat and whisk until the sugar’s dissolved. You won’t need all of the syrup, and you can save and use any leftovers to sweeten your beverages.

The Ganache

At the Omni Parker House, the chefs glaze the top of the cake with chocolate fondant icing that’s feathered with white fondant icing. This all looks lovely, but I much prefer a rich ganache to the fondant icing that’s traditionally used. Most ganache recipes will have you pour scalding cream over your chocolate before using a whisk or immersion blender to emulsify it with room temperature butter. Many pastry chefs will use a bain marie for this task, as the vertical, metal container is better at maintaining heat, ensuring the cream properly melts the chocolate. While I do think that is the superior method if you work in a commercial kitchen—as the blade of the immersion blender is the best for emulsifying chocolate and creates silky ganaches—most home cooks don’t have a bain marie at home. 

Instead, it’s easier and more practical for most people to just use a heat-proof bowl at home. But simply pouring hot cream over the ganache to melt it isn’t efficient in a bowl, as its wide opening allows heat to escape quickly and cools the chocolate before it’s had a chance to even melt properly. The faster and foolproof way to get a silky ganache at home? Preparing it with a double boiler. 

Just as you’d melt chocolate by placing a bowl of it on top of a saucepan of simmering water, the most foolproof method for making ganache without a bain marie and immersion blender is to melt the chocolate and cream together in a bowl set atop barely simmering water. This helps to evenly heat the cream and melt the chocolate. Once the chocolate is melted, you’ll want to cool it slightly. 

Ganache that’s too hot will just run right off a cake; you want to cool it to about 35ºC or 95ºF so it’s still pourable but thick enough to cling to the cake.

(If your chocolate has cooled too much, you can reheat it with the double boiler until you reach your desired texture. Alternatively, you can microwave it in 5 to 10 second increments until melted.)

I add a teaspoon of corn syrup, which gives the ganache additional shine, and a touch of salt just to balance the sweetness of the cake. Dark chocolate is my chocolate of choice here, as it tends to have a pleasant bittersweet and fruit flavor, but if you’d prefer a glaze on the sweeter side, you’re more than welcome to experiment with milk chocolate.

Assembling the Cake

Besides baking the actual cake, assembling a layer cake is possibly the most intimidating part for most home bakers. Most layer cakes would have you level the cake, stack it with whatever buttercream or frosting you’re using, then crumb coat and refrigerate it. Luckily for us, a Boston cream pie requires no crumb coat. You really just have to brush the cake with simple syrup, sandwich a generous layer of pastry cream, then glaze the top of the cake with chocolate ganache. You can use an offset spatula to spread it neatly across the top or create decorative drips down the cake. 

My version of Boston cream pie may have a few differences from the original, but it’s a whole lot easier—and just as satisfying to eat. And you didn’t even have to travel to Boston for it.