I had never tried Boston cream pie before making this recipe. Not being a huge fan of custards, I was hesitant that I would like it. That said, I was pleasantly surprised that everyone including myself enjoyed this cake. I know this recipe has 3 parts to it that may seem labor-intensive but I urge you not to be intimidated and give it a shot.
Boston Cream Pie
2c scalded milk
1 tsp vanilla
2 eggs, separated
1c cake flour*sifted
1 tsp baking powder
pinch of salt
1/2c hot milk
1 tbsp butter
2 oz unsweetened chocolate
1 tbsp butter
1 to 1 1/2 pounds of powdered sugar
Cream filling (Needs time to cool so, make ahead)
In a heat-proof bowl whisk together all of the ingredients for the cream filling except for the milk and vanilla until well incorporated. Slowly stream in your hot milk while whisking constantly. Cook over a double boiler (pot your bowl fits on top with 2 inches of simmering water) whisking frequently until really thick. This took about 30 minutes for me, it could take more or less time depending. When ready add the vanilla and transfer it to a container and place plastic wrap on the top of the cream to prevent a skin from forming. Let come to room temp then transfer to the fridge to cool completely.
Preheat oven to 350F. Melt your butter and heat with your milk, and reserve for later. Combine the flour, baking powder, and salt in a bowl, and set aside. In the bowl of a stand mixer or using a hand mixer whip the egg whites until stiff peaks. Add in the egg yolks and keep beating until incorporated and fluffy. Slowly stream in sugar while the mixer is running. Continue beating the mix for another 2 minutes. Add in the dry ingredients then once almost all is incorporated add your hot milk and butter. Pour into a prepared 8-inch cake pan and bake for 25 minutes or until a toothpick comes out clean. Cool completely
Combine your ingredients over a double boiler and heat until the chocolate is melted and the mixture is smooth. Remove from heat and add vanilla, and allow to cool until lukewarm. Add in powdered sugar until desired consistency. You can add enough to make the frosting spreadable like the recipe states but if you want more of a looser drip consistency add less powdered sugar. I would half this recipe if you only want the top frosted because it makes more than you need for that application
Slice your cake in half crosswise and fill it with the cream. I suggest refrigerating before frosting to help keep the layers from sliding but if you’re pressed for time just be gentle. When ready frost your cake and store it in the refrigerator.
*If you don’t have cake flour you can just measure out 1c all-purpose flour, remove 2 tbsp and add 2 tbsp cornstarch to replace the flour you took out.
**Feel free to use a ganache in place of the frosting