Name: Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe
Prep time: 30 min
Cook time: 35 min
Total time: 2 h 35 min
Cuisine: American
Ingredients: 300 g Granulated sugar; 113 g Unsalted butter (at room temperature); 110 g Oil; 3 Eggs (at room temperature); 240 g Greek yogurt (at room temperature); 1 teaspoon Vanilla extract; 375 g All purpose flour; ½ teaspoon Salt; 1 teaspoon Baking powder; 1 teaspoon Baking soda; 960 g Whole milk (3% fat); 200 g Granulated sugar; 160 g Egg yolk (approximate yolk of 8 eggs); 50 g Corn starch; 50 g All purpose flour; ½ tablespoon Vanilla extract; 110 g Unsalted butter (82% fat, at room temperature); 115 g Heavy cream (36% fat content, cold); 230 g Semi-sweet chocolate; 230 g Heavy cream (36% fat content); 1 tablespoon Vegetable oil

Jump to Recipe· 4.3 from 51 reviews

If you have a soft spot for desserts that are both nostalgic and decadently delicious, you are going to absolutely fall in love with this Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe. This cake is a beautiful twist on the classic Boston Cream Pie, offering layers of moist vanilla sheet cake soaked with luscious pastry cream hidden beneath a silky diplomat frosting and topped with a glossy chocolate ganache. It’s an irresistible blend of textures and flavors that effortlessly elevates any occasion.

Ingredients You’ll Need

The image shows four stages of mixing batter in a white bowl placed on a white marbled surface. The first stage has a white electric mixer blending a yellowish mixture while a glass measuring cup with a clear liquid is poured in. In the second stage, three cracked eggs are being poured from a glass bowl into the same bowl while the mixer blends the light yellow batter. The third stage shows a pink spatula folding white whipped cream into the thickened yellow batter in the bowl. The final stage has a woman's hand holding an empty glass bowl above the mixed batter while the mixer is ready to blend the mixture. photo taken with an iphone --ar 4:5 --v 7

Gathering simple yet essential ingredients is the first step to making this Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe shine. Each element adds a unique touch — from the rich buttery cake base to the creamy, velvety layers and the smooth chocolate finish.

Granulated sugar: Sweetens both the cake and the pastry cream perfectly without overpowering other flavors.
Unsalted butter: Adds richness and tenderness to the cake and pastry cream; ensure it’s at room temperature for smooth mixing.
Oil: Keeps the cake moist and tender beyond just the butter’s contribution.
Eggs: Provide structure and bind the cake ingredients together; room temperature eggs mix better.
Greek yogurt: Adds moisture with a slight tang, enhancing the cake’s softness.
Vanilla extract: Infuses the cake and creams with warm, inviting flavor.
All-purpose flour: Forms the body of the cake and thickens the pastry cream.
Salt: Balances the sweetness and amplifies flavor.
Baking powder and baking soda: Help the cake rise perfectly fluffy.
Whole milk: Used in the pastry cream for that classic, smooth texture.
Egg yolks: Make the pastry cream rich and creamy.
Corn starch: Thickens the pastry cream to the ideal consistency.
Heavy cream (36% fat): Whipped to lighten the diplomat frosting and for the ganache’s silky finish.
Semi-sweet chocolate: Provides a bittersweet counterpoint in the ganache topping.
Vegetable oil: Added to the ganache for that perfect shiny, smooth texture.

How to Make Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe

Step 1: Bake the Vanilla Sheet Cake

Start by preheating your oven to 175℃ (350℉) and preparing a 9×13-inch pan by greasing it or lining it with parchment paper. Cream together room-temperature butter and granulated sugar until you reach a light and fluffy texture. Add oil, eggs one at a time, followed by Greek yogurt and vanilla extract for that tender crumb and subtle tang. Carefully sift in the dry ingredients—flour, baking powder, baking soda, and salt—and fold just until combined to keep the cake airy. Pour your batter into the pan and bake for about 35 minutes or until a toothpick comes out clean. This cake’s moist and tender crumb is the perfect canvas for the luscious layers to come.

Step 2: Make the Pastry Cream

While the cake bakes, whisk the sugar and egg yolks until pale and fluffy to start the pastry cream. Add cornstarch, flour, and vanilla, mixing until smooth. Heat the milk just until it simmers, then slowly temper the yolk mixture by whisking in the hot milk—this prevents scrambled eggs and ensures a silky custard. Return everything to the heat and stir continuously until thickened to the perfect pudding-like consistency. For an ultra-smooth finish, strain it and then whisk in softened butter. Divide your pastry cream: half for filling the poke holes in the cake while still warm, and half reserved for making the diplomat frosting later.

Step 3: Poke and Fill the Cake

Once your cake emerges from the oven, grab the handle of a wooden spoon and pierce holes evenly across the top. Immediately pour half of the warm pastry cream over the cake, gently filling each hole with that creamy goodness. Letting it soak in while the cake cools ensures every forkful is bursting with flavor.

Step 4: Prepare the Diplomat Frosting

Whip the cold heavy cream to soft peaks, making sure not to overdo it, so you maintain a light texture. Loosen the reserved pastry cream with a few swift whisk strokes, then carefully fold in the whipped cream with a spatula, creating the lighter diplomat frosting. Spread this delightful layer evenly across the cooled cake and pop it into the fridge while you prepare the final chocolate glaze.

Step 5: Make the Chocolate Ganache Glaze

Semi-melt your semi-sweet chocolate in short bursts in the microwave, stirring between each to avoid burning. Heat the cream just until it’s about to simmer and pour it over the melted chocolate. Stir gently until smooth and glossy, then add vegetable oil to enhance the shine and texture. Allow your ganache to cool slightly until thick but pourable, then spread over the diplomat frosting. Chill the entire cake for at least 4 hours to let the layers set beautifully.

How to Serve Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe

A square slice of cake sits on a white plate with a speckled rim, resting on a white marbled surface. The cake has three visible layers: the bottom layer is a light golden sponge with a soft, crumbly texture; above it is a thick creamy layer of pale yellow custard with a smooth, slightly glossy finish; the top layer is a shiny, dark chocolate glaze that is evenly spread, with the edges slightly dripping down the sides. Part of the top right corner has a bite taken out, showing the layers distinctly. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

While this cake looks stunning all on its own, a few well-chosen garnishes can elevate it even more. Fresh berries like raspberries or sliced strawberries add a bright pop of color and a subtle tartness that pairs wonderfully with the rich creams and chocolate. A dusting of powdered sugar or edible flowers can also lend a delicate, fancy touch that makes every slice feel special.

Side Dishes

This Boston Cream Poke Cake pairs exceptionally well with a cup of strong coffee or an espresso, balancing the dessert’s sweetness with a touch of bitterness. For a lighter accompaniment, a glass of cold milk or an herbal tea like mint or chamomile complements the creamy layers without overpowering them.

Creative Ways to Present

Serve the cake on a beautiful cake stand to showcase the glistening chocolate ganache. Cut into neat squares to highlight the puddles of pastry cream filling, letting the layers peek through invitingly. For a fun twist, serve individual portions in clear glass dishes to show off the layers, or add a scoop of vanilla bean ice cream alongside each serving for an extra indulgent treat.

Make Ahead and Storage

Storing Leftovers

After enjoying your Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe, be sure to store any leftovers covered in the fridge. Airtight containers or well-wrapped foil and plastic wrap keep the cake fresh for 1 to 2 days, preserving the moist texture and creamy layers without drying out.

Freezing

This cake is best enjoyed fresh, but if you must freeze, wrap individual slices tightly in plastic wrap and then a layer of aluminum foil to prevent freezer burn. Place them in a freezer-safe container or bag. When you’re ready, thaw in the refrigerator overnight to maintain the creamy texture without becoming soggy.

Reheating

Because of the delicate cream layers and ganache, reheating is generally not recommended. Instead, let your cake come to room temperature for about 20 to 30 minutes before serving to soften the frosting and bring out the best flavors.

FAQs

Can I use regular yogurt instead of Greek yogurt in the cake?

Yes, you can substitute regular yogurt, but Greek yogurt adds extra creaminess and tang that enhances the cake’s texture. If using regular yogurt, you might want to strain it briefly to thicken it.

Is it possible to make this cake gluten-free?

To make this Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe gluten-free, substitute the all-purpose flour with a gluten-free flour blend that measures cup-for-cup. Just make sure to test the batter consistency as gluten-free blends can sometimes require tweaks.

Can the pastry cream be made ahead of time?

Absolutely! Pastry cream can be prepared a day in advance, covered tightly with plastic wrap pressed onto the surface to prevent a skin from forming, and refrigerated until ready to use.

What type of chocolate works best for the ganache?

Semi-sweet chocolate is ideal because it provides the perfect balance between sweet and bitter, complementing the creamy elements without being too sugary or too dark.

How can I tell when the cake is done baking?

The best way is to insert a toothpick into the center of the cake; if it comes out clean or with a few moist crumbs, your cake is perfectly baked. Avoid overbaking to maintain moistness.

Final Thoughts

This Boston Cream Poke Cake with Pastry Cream, Diplomat Frosting, and Chocolate Ganache Recipe is a delightful celebration of classic flavors with a fresh, modern approach. It’s the kind of dessert that truly feels like a warm hug after a meal and a guaranteed crowd-pleaser for any occasion. I encourage you to give it a try — you might just find your new favorite cake to bake and share with those you love.