Position oven rack in center of oven. Preheat oven to broil (or high broil). Spray sides of a 9-inch springform pan with baking spray with flour. Line bottom of pan with parchment paper.

For cake: In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites at medium-high speed until foamy, about 1 minute. With mixer on medium speed, gradually add ½ cup (100 grams) sugar and salt. Increase mixer speed to medium-high speed, and beat until stiff peaks form, 1 to 2 minutes. Transfer egg white mixture to a large bowl. Clean bowl, and return to mixer.

In a small microwave-safe bowl, heat marzipan on high until softened, 15 to 30 seconds.

In the bowl of a stand mixer fitted with the paddle attachment, beat softened marzipan, butter, and remaining ¾ cup (150 grams) sugar at medium speed until light and creamy, 2 to 3 minutes, stopping to scrape bottom and sides of bowl. With mixer on medium-high speed, add egg yolks, one at a time, beating until combined after each addition and stopping to scrape sides of bowl. Beat in rum or liqueur and vanilla. Beat in almond extract (if using).

In a medium bowl, sift together cornstarch, flour, baking powder, cinnamon, and nutmeg. Using a rubber spatula, fold half of cornstarch mixture into marzipan mixture. Fold in half of egg white mixture. Repeat with remaining cornstarch mixture and remaining egg white mixture. Spread ½ cup (95 grams) batter into bottom of prepared pan.

Broil until golden brown on surface, about 2 minutes. (Do not walk away; this happens fast!) Immediately spread another layer of batter on top of first, and broil until golden brown on surface, about 2 minutes. Repeat procedure with remaining batter. (The first few layers may take longer to cook, but the more layers added, the closer to the heat source and the faster they cook.) Let cool in pan for 10 minutes. Gently run a knife between sides of pan and cake; remove sides of pan. Let cake cool completely on pan on a wire rack.

For topping: In a small microwave-safe bowl, heat preserves on high in 15-second intervals, stirring between each, until fluid. Using a pastry brush, brush a thin layer of preserves on top and sides of cooled cake. Let stand until preserves are set and just tacky, about 30 minutes.

In a small saucepan, heat cream over medium-low heat just until beginning to steam. (Do not boil.)

In a medium heatproof bowl, combine hot cream, chocolate, and butter; let stand for 5 minutes. Stir until chocolate and butter are melted and mixture is smooth. Pour onto cake, using an offset spatula to smooth top and spread on sides. Let stand for 5 minutes. Press almonds onto side of cake. Let stand until ganache is completely set, about 20 minutes at room temperature or 10 to 15 minutes in refrigerator, before serving. Refrigerate in an airtight container for up to 3 days.