SO MANY PEOPLE love bananas, and combined with chocolate it’s a match made in heaven for children and adults alike. But sadly, as all of my chefs have learned, I haven’t yet trained my palate to enjoy the soft, rich fruit. That, however, doesn’t mean I will deny my guests the opportunity to enjoy it! Here we ponder, will a chocolate cake cut into thirds weigh less than the sum of its parts? For the look, certainly. This destructured chocolate ganache cake mingles with fresh bananas, a vanilla-lime sorbet, and lime zest confit. Smooth and vibrant, intense and creamy—a flourless sweet and sour composition that is so popular, I might change my mind!
    Lime Zest Confit (makes extra/4-day process)
    Flourless Cocoa Biscuit
    Chocolate-Banana Ganache
    Caramel Chocolate Crémeux
    Lime Sauce
    Vanilla-Lime Sorbet (makes about 1 quart)
    For the Lime Zest Confit
    1. Cut the limes in half, extract and reserve the juice, and carve out the flesh from the interior, taking care to not puncture the rind.
    2. Place the rind in a medium saucepan, cover with cold water, and bring to a simmer. Simmer for 5 minutes. Strain and repeat 4 more times. Strain the water from the pan and pour in the reserved juice, 1 quart of water, and 4 cups of the sugar; simmer until the sugar is dissolved.
    3. Remove from the heat, cover, and rest at room temperature overnight. For each of the next 2 days, add another 1 cup of sugar, simmer until dissolved, and cover again. On the third day, add the remaining sugar with the corn syrup and simmer until dissolved. Reserve the rinds in the liquid, refrigerated, for up to 1 month. Strain the rind and cut into triangles before serving.
    For the Dark Chocolate Décor
    1. Spread a 1-millimeter layer of chocolate to cover the acetate. Rest for 5 minutes, or until the chocolate has begun to set but still remains flexible. With a paring knife, quickly form triangles from the chocolate by scoring on a diagonal at 2-inch widthwise intervals, then drape the acetate, chocolate side out, over the tube. Let the chocolate harden overnight for best results.
    For the Flourless Cocoa Biscuit
    1. Preheat the oven to 390°F. Line the bottom of a 9½ × 13-inch rimmed baking sheet with a Silpat and coat with a thin layer of nonstick cooking spray.
    2. In the bowl of an electric mixer fitted with a whisk, whip the egg yolks with 7 tablespoons of the sugar until it forms ribbons, sift in the cocoa powder, and whip on low speed until no streaks remain. Transfer the mixture to a large bowl and set aside. Clean the bowl of the electric mixer and add the egg whites with one-third of the remaining sugar. Whip on medium speed until foamy. Gradually stream in the remaining sugar, while continuing to whip to reach soft peaks.
    3. Gently fold the egg whites into the yolk mixture in 3 additions, until no streaks remain but it is still light and fluffy. Pour the batter onto the prepared baking sheet and spread into a flat layer with a spatula. Bake for 8 to 10 minutes, until a cake tester inserted into the center is clean when removed. Run a knife along the edges of the biscuit to loosen and flip it out onto a rack to cool.
    4. Return the biscuit to a parchment paper–lined 9½ × 13-inch rimmed baking sheet and freeze.
    For the Chocolate-Banana Ganache
    1. Soak the gelatin sheets in ice water for 10 minutes; squeeze dry.
    2. Fill one-third of a medium saucepan with water and bring to a simmer. Place the chocolate in a heatproof bowl and set on top of the saucepan. Warm until melted, stirring occasionally, then remove from the heat. With a spatula, pass the banana through a drum sieve into the chocolate. In a small saucepan, bring the heavy cream and sugar to a simmer. Add to the melted chocolate and puree with a hand blender until smooth to make a ganache. Pour the ganache over the chocolate biscuit, spread to an even layer, and return to the freezer until solid, then cover.
    For the Caramel Chocolate Crémeux
    1. Fill one-third of a medium saucepan with water and bring to a simmer. Place the chocolate in a heatproof bowl and set on top of the saucepan. Stir until melted; keep warm. In a medium heavy-bottomed saucepan, combine the sugar and corn syrup and heat, stirring occasionally, to a dark caramel color, 355°F. Remove from the heat and carefully (it will spatter) add the heavy cream and butter. Return to low heat and stir until smooth. Pour the caramel mixture into the chocolate and puree with a hand blender until smooth. Pour onto the tray of frozen biscuit and ganache and spread into an even layer to finish layering the gâteau. Return to the freezer until solid, about 4 hours.
    To Portion the Gâteau
    1. Run a knife around the edges of the layered gâteau and lift onto a cutting board. Cut lengthwise into two 3-inch strips and trim the edges. Cut each strip into 8 triangles with 2-inch bases, making 24 total. Transfer to the refrigerator to thaw, about 3 hours.
    For the Lime Sauce
    1. In a small bowl, combine the sugar and pectin. In a small saucepan, bring the lime juice to a simmer and whisk in the sugar mixture. Simmer for 1 minute, strain through a fine-meshed sieve, and reserve, chilled.
    For the Vanilla-Lime Sorbet
    1. In a medium saucepan, combine 1½ cups water with the vanilla seeds, sugar, trimoline, and glucose powder. Stir until the sugar is dissolved. Pour into a bowl set over ice and stir until well chilled. Stir in the lime juice. Spin in an ice cream machine according to the manufacturer’s instructions.
    To Finish
    1. Just before serving, cut the bananas into 1-inch batons and toss with the lime zest and juice.
    2. For each serving, arrange 3 slices of gâteau, several dots of lime sauce, and a few lime confit triangles on a chilled dessert plate. Top each slice of gâteau with a piece of banana and a chocolate décor triangle. Scoop a spoonful of ice cream on top of a piece of lime zest confit.