Banana-Split Ice Cream Cake

Cake: In a small bowl, combine 2 tablespoons vanilla extract and 2 tablespoons water. Sprinkle with gelatin; let stand 5 minutes. Combine egg yolks and 1/2 cup granulated sugar in a heatproof bowl set over (but not in) a pot of simmering water. Whisk until pale and thickened, about 2 minutes. Whisk in gelatin mixture until dissolved. Transfer mixture to a cool bowl.

Beat 2 1/2 cups cream with vanilla seeds on medium‐high speed to stiff peaks. Fold one third of whipped cream into gelatin mixture, then fold gelatin mixture into remaining cream.

In a clean mixing bowl, beat egg whites on medium‐high speed to soft peaks. Gradually add 1/2 cup granulated sugar and beat to stiff peaks, 5 to 6 minutes. Fold into cream mixture. (You should have about 9 cups total.)

Line a 9‐by‐13‐inch baking pan with plastic wrap, leaving a 4‐inch overhang on all sides. Arrange 18 cookies on bottom of pan, slightly overlapping. Arrange bananas over wafers in a single layer. Spread 4 cups cream mixture on top. Arrange 12 more cookies on top of cream. Fold halved cherries into remaining cream, then spread over cookies. Arrange remaining 12 cookies on top. Wrap in plastic and freeze at least 4 hours and up to 3 days.

Caramel: In a small saucepan, stir together remaining 1 cup sugar, 1/4 cup water, and salt. Heat over medium, gently stirring occasionally, until sugar has dissolved and syrup is clear. Cook, without stirring, washing down sides of pan with a wet pastry brush a few times to prevent crystals from forming, until syrup comes to a boil. Continue to cook, gently swirling pan occasionally, until syrup is dark amber, 8 to 10 minutes.

Remove caramel from heat; carefully pour in 1/2 cup cream (it will bubble). Stir in remaining 1/2 teaspoon vanilla until smooth. Let cool completely. Sauce can be refrigerated in an airtight container up to 2 weeks; reheat in microwave or a small pot before serving.

Assembly: Remove cake from freezer; invert onto a platter, using plastic to pull out (if it's sticking, rub sides and bottom of pan with a warm, moist kitchen towel to loosen). Remove plastic; if desired, trim cake edges. Drizzle with 1/2 cup caramel. Beat remaining 1 cup heavy cream with confectioners' sugar on medium‐high speed to stiff peaks; dollop over cake. Sprinkle with chopped walnuts and whole cherries; serve immediately with remaining caramel on the side.