How to Make It
Preheat the oven to 350°. Line a 9-inch springform pan with a round of parchment paper. In a microwave-safe bowl, combine the chocolate with the butter and melt at high power, stirring every 20 seconds, until smooth. Let cool slightly. Whisk in the cocoa powder, brown sugar and vanilla. Add the 5 egg yolks one at a time, whisking well between additions.
In a stand mixer fitted with the whisk, beat the egg whites with the salt at medium-high speed until frothy. Reduce the speed and add the granulated sugar in a thin stream. Beat the whites at medium-high speed until stiff and glossy.
Scoop one-fourth of the meringue into the chocolate mixture and mix until thoroughly combined. Gently fold in the remaining meringue just until no white streaks remain. Scrape the batter into the prepared pan. Bake until the cake is firm at the edge and the center is still slightly jiggly, about 30 minutes. Let cool to room temperature on a rack; as the cake cools, the center will sink, forming a bowl shape. Cover and refrigerate until slightly chilled, about 1 hour.
In a medium heatproof bowl, beat the egg yolks with the cornstarch, salt, 1/2 cup of the sugar and the vanilla bean seeds until pale and smooth. In a medium saucepan, bring the milk just to a simmer with the remaining 1/4 cup of sugar and the vanilla bean. In a slow stream, carefully beat one-third of the hot milk into the egg mixture, whisking constantly. Discard the vanilla bean. Scrape the egg mixture into the saucepan and bring to a boil over moderately high heat, whisking constantly and vigorously, until the pudding is smooth and very thick. Once the pudding boils, continue whisking for 2 minutes longer. Pour the pudding into a large bowl and press a piece of plastic wrap directly onto the surface. Let cool slightly, then refrigerate for at least 1 hour, until chilled and firm.
Stir the chilled pudding with a rubber spatula until creamy and smooth. In a medium bowl, whip the cream until soft peaks form. Stir one-third of the whipped cream into the pudding, then gently fold in the remaining whipped cream until no streaks remain. Fold in the bananas.
Run a knife around the edge of the cake and remove the ring. Carefully invert the cake onto a flat cookie sheet. Remove the pan bottom and peel off the parchment paper. Transfer the cake to a serving plate right-side-up. Gently mound the banana pudding in the center of the cake, forming a smooth dome. Refrigerate until chilled, at least 1 hour.
In a medium microwave-safe bowl, heat the condensed milk with the chocolate, stirring every 20 seconds, until melted and smooth. Stir in the vanilla and salt. Transfer to a piping bag fitted with a 1/4-inch plain tip.
In a medium microwave-safe bowl, heat the condensed milk with the peanut butter, stirring every 20 seconds, until smooth. Stir in the heavy cream and the salt. Transfer to a piping bag fitted with a 1/4-inch plain tip.
Pipe stripes of the peanut butter topping over the pudding, then follow with perpendicular lines of fudge topping. Cut the cake into wedges and serve. Pass any remaining fudge and peanut butter toppings, along with cherries, strawberries and whipped cream.
The chocolate cake, banana pudding and both toppings can be refrigerated for up to 2 days. Melt the toppings slightly before using.
Dutch process cocoa powder has been treated with an alkali, which neutralizes its natural acidity. As a result, it retains its nearly black color during baking and has a mellower flavor.