• Preheat oven to 350 degrees. Line an 8-inch round cake pan with parchment paper, and spray with cooking spray.
• Combine 3 tablespoons sugar and the egg yolks in bowl of an electric mixer fitted with the whisk attachment; whisk, on medium speed, until pale yellow and thick, about 15 minutes. Add vanilla, and fold in melted chocolate just to combine.
• In a medium bowl, combine egg whites and pinch of salt in bowl of electric mixer; whip, on medium speed, until frothy. Add remaining 3 tablespoons sugar; beat until stiff. Fold egg whites into the chocolate mixture.
• Carefully pour batter out into prepared cake pan. Bake until cake is set and top is dull, about 20 minutes. Remove from oven, and let cool on a wire rack.
• Spray a 5-cup-capacity metal bowl with cooking spray; line with plastic. Pack base of bowl with pistachio ice cream; layer cherry ice cream over pistachio, then finish with another layer of pistachio ice cream (or layer ice creams and sorbets as you desire). Pack firmly, cover surface with plastic wrap, and place in freezer.
• Freeze until ice cream is very hard, at least 2 hours or up to 24 hours in advance. Place cake on a parchment-lined baking sheet. Remove ice cream from the freezer, and invert bowl over cake. Keep the ice cream covered with plastic wrap, and return ice-cream cake to the freezer.
• Preheat oven to 500 degrees. Fill a pastry bag, fitted with an Ateco #5 star tip, with meringue; pipe onto ice cream in a decorative fashion, or spoon meringue over ice cream and swirl with a rubber spatula. If ice cream starts to soften, return cake to freezer for 15 minutes.
• Place in oven, and bake until meringue just starts to brown, 1 to 2 minutes. Remove from oven, and serve immediately.

Swiss Meringue

• Fill medium saucepan one quarter full with water. Set the saucepan over medium heat, and bring water to a simmer.
• Combine egg whites, sugar, and cream of tartar in the heatproof bowl of electric mixer, and place over saucepan. Whisk constantly until sugar is dissolved and whites are warm to the touch, 3 to 3 1/2 minutes. Test by rubbing between your fingers.
• Transfer bowl to electric mixer fitted with the whisk attachment, and whip, starting on low speed, gradually increasing to high until stiff, glossy peaks form, about 10 minutes. Add vanilla, and mix until combined. Use meringue immediately.