Prinzregententorte (Bavarian Layer Cake) vs Classic Boston Cream Pie

Both cakes rely on a cornstarch-thickened custard of milk, egg yolks and sugar, but they take it in opposite directions. In the Prinzregententorte it is beaten into creamed butter with cocoa (and optional rum) to make a firm chocolate buttercream spread between eight thin cocoa sponge layers; the stacked cake is then brushed with apricot jam and covered in a dark chocolate and cream glaze. The Boston Cream Pie keeps its vanilla custard as a soft, chilled pastry cream sandwiched between two thicker baking-powder sponges, topped with a glossy chocolate glaze made with cream and corn syrup that drips down the sides. One is a chocolate-forward slice of many fine layers; the other is a creamy contrast of vanilla and chocolate.