Boozy Cherry and Chocolate Pavlova

Place a rack in middle of oven; preheat to 300°. Beat 6 large egg whites, 1¾ cups (350 g) sugar, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and ¼ tsp. cream of tartar in the bowl of a stand mixer fitted with the whisk attachment on medium-low speed until egg whites are foamy and sugar is partially dissolved, about 5 minutes.

Increase speed to medium and continue to beat, scraping down sides of bowl halfway through, until sugar is dissolved, medium-stiff peaks have formed, and meringue is opaque, shiny, and thick, 12–15 minutes (rub a small amount of meringue between 2 fingers; it should feel fairly smooth with only a few tiny grains of sugar if any).

Stir together 1 Tbsp. plus 1 tsp. cornstarch and 1 Tbsp. distilled white vinegar in a small bowl until dissolved. Add 1 (heaping) Tbsp. meringue and stir to combine. Pour into bowl with remaining meringue and fold with a rubber spatula until incorporated.

Scrape meringue onto a parchment-lined rimmed baking sheet. Using a small offset spatula, spread meringue into a 10x8" rectangle, about 1½" thick. Smooth top of rectangle flat. Using a rubber spatula, pull meringue upward in short strokes along all 4 sides to create grooves in the meringue. Dab small dollops of leftover meringue under each corner of parchment to help adhere it to baking sheet.

Bake meringue 15 minutes, then reduce oven temperature to 275° and continue to bake until top of meringue feels crisp and dry to the touch and edge of meringue lifts easily from parchment paper, 70–80 minutes more. Let cool. Do Ahead: Meringue can be made 4 hours ahead. Store, uncovered, at room temperature.

Cook juice of 1 large lemon, 2 lb. frozen cherries, preferably a mix of sweet and tart, 1½ cups (300 g) sugar, ½ cup red wine vinegar, and ¼ cup brandy in a large saucepan over medium heat until cherries are thawed, 8–10 minutes. Using a slotted spoon, transfer cherries to a medium bowl. Bring syrup to a boil and cook, stirring occasionally, until reduced by half, 12–15 minutes. Let syrup cool slightly, then pour over cherries and let cool completely. Do Ahead: Cherries can be cooked 2 days ahead. Cover and chill.

Bring ⅔ cup heavy cream to a boil in a small saucepan over medium heat. Remove from heat, add 4 oz. bittersweet chocolate (70% cacao), chopped, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt and whisk until smooth and glossy. Scrape ganache into a small bowl and let cool. Do Ahead: Ganache can be made 2 days ahead. Cover and chill.

Using an electric mixer on medium speed, beat 2 cups heavy cream, 2 tsp. vanilla bean paste or vanilla extract, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt in a large bowl until soft peaks form, about 2 minutes (alternatively, vigorously whisk by hand).

Drain cherries (reserving syrup for another use). Carefully transfer meringue to a platter. Drizzle half of ganache over meringue. Spoon whipped cream over, piling high. Drizzle remaining ganache over whipped cream. Scatter cherries over cream. Using a vegetable peeler, shave chocolate into curls from 1 thick bar (at least 6.35 oz.) bittersweet chocolate (about 70% cacao) on top if desired