Make the Meringue: Preheat the oven to 120°C (250°F) and line a baking tray with parchment paper. In a clean, dry bowl, beat the egg whites with an electric mixer until soft peaks form. Gradually add the sugar, one tablespoon at a time, beating well between additions until stiff peaks form and the mixture is glossy. Gently fold in the cornstarch, vanilla extract, and apple cider vinegar until just combined. Spoon the meringue onto the prepared baking tray, shaping it into a round or oval base with slightly raised edges to hold the topping. Bake for 1 hour and 15 minutes, then turn off the oven and let the meringue cool completely inside the oven with the door slightly ajar.
2. Prepare the Peach Topping: In a medium saucepan, combine the peaches, sugar, cinnamon, vanilla, and water. Cook over medium heat, stirring gently, until the peaches start to release their juices. In a small bowl, mix the cornstarch with 1-2 tbsp of water to create a slurry, then stir it into the peach mixture. Cook for another 2-3 minutes, or until the sauce thickens and coats the peaches. Remove from heat and let cool.
Whip the Cream: In a chilled bowl, whip the heavy cream until soft peaks form.
Assemble the Pavlova: Place the cooled meringue base on a serving plate. Spread the whipped cream evenly over the meringue. Spoon the peach topping generously over the whipped cream. Serve immediately and enjoy the perfect balance of crunchy meringue, fluffy cream, and sweet peaches!