Prepare Cake Pans and Oven: Preheat your oven to 180°C (350°F) or 160°C (320°F) for fan ovens. Grease three 20cm (8-inch) round cake pans thoroughly and line the bottoms with parchment paper to prevent sticking.
Combine Dry Ingredients: Sift together the cocoa powder and all-purpose flour into a mixing bowl. Set aside this dry mixture to incorporate later.
Whip Eggs and Sugar: Using a stand mixer with a whisk attachment or an electric hand mixer, beat the eggs on medium-high speed for 30 seconds. Gradually add the superfine sugar over 45 seconds while continuing to whisk. Add vanilla extract, then increase the speed and beat for approximately 7 minutes, or until the mixture triples in volume and becomes pale and fluffy. This aeration step is crucial to the cake's rise as there is no baking powder.
Gently Fold Dry Ingredients: Using a spatula, gently fold the sifted flour and cocoa mixture into the whipped eggs in small batches. Be careful not to deflate the batter—some streaks of flour remaining are acceptable.
Incorporate Melted Butter: Slowly fold the cooled melted butter into the batter until fully combined and smooth. Avoid overmixing to maintain the airy texture.
Bake the Cake Layers: Divide the batter evenly among the prepared pans, pouring into the center and allowing it to spread evenly. Bake in the preheated oven for about 25 minutes or until a toothpick inserted into the center comes out clean and the cake springs back lightly when touched.
Cool the Cakes: Allow the cakes to cool in their pans for 10 minutes. Then carefully invert them onto a wire rack to cool completely before assembling.
Prepare Cherry Syrup: Drain the cherries, reserving their syrup. In a small bowl, mix 1/4 cup of the reserved cherry syrup with cornstarch to create a slurry. In a saucepan over medium-low heat, combine the sugar, 1/3 cup reserved syrup, and bring to a gentle simmer until the sugar dissolves. Stir in the cornstarch slurry and cook for another minute, stirring constantly until thickened. Remove from heat, stir in kirsch or additional syrup if using, then mix with the drained cherries and allow to cool.
Make Chocolate Curls: Break chocolate into small pieces and gently melt in a microwave-safe bowl with short bursts, stirring often. Spread melted chocolate thinly on the back of a baking sheet and refrigerate for 3-4 minutes until partially set. Using a bench scraper or a knife held at an angle, scrape along the surface to form curls. Refrigerate curls until needed.
Whip Cream: Shortly before assembling, whip the heavy cream with vanilla and powdered sugar until stiff peaks form. Chill until ready to use.
Assemble the Cake: Place one cake layer upside down on your serving plate or a cake turntable. Brush generously with 1/4 cup of the cherry syrup. Spread 1 cup of whipped cream evenly, leaving a small border around the edge. Layer half of the cherries on top using a slotted spoon. Repeat with the second layer: invert, brush with syrup, spread cream, and add remaining cherries. Top with the third cake layer.
Frost and Decorate: Cover the entire cake with the remaining whipped cream, smoothing the sides and top. Pipe decorative cream dollops around the top edge using a star tip, placing one cherry atop each. Pile chocolate curls in a decorative mound in the center and press smaller shavings around the cake base.
Chill for Flavor Development: Refrigerate the cake for at least 4 hours, preferably overnight, to allow the syrup to soak in and flavors to meld beautifully.
Serve: Remove the cake from the fridge about 30 minutes before serving to soften the cream slightly for the best texture. Slice and enjoy!