For the Pavlova: Preheat the oven to 225°F. Prepare a baking sheet with parchment paper. On the parchment paper, draw six 4" circles. Flip the parchment so the ink side is facing the sheet pan, and set aside.
Add egg whites to the bowl of a stand mixer fitted with a whisk attachment and beat on medium-high speed until the egg whites have soft peaks. With the mixer running on high speed, slowly add in the sugar, 1 tablespoon at a time. Once all the sugar is incorporated, continue to mix for 8 to 10 minutes until glossy, stiff peaks form.
Remove from the mixer and fold in the cornstarch, lemon juice, vanilla, and salt. Place into a piping bag fitted with a star tip and pipe hearts onto the parchment paper circles. Bake for 1 hour and 15 minutes. Turn the oven off, leaving the pavlova in the oven for 35 minutes longer. Remove from the oven and allow to cool.
For the POM Curd: In a medium saucepan, combine the POM Arils, cranberries, POM Juice, and sugar over medium heat and cook for 10 minutes.
Transfer the mixture to a blender or food processor and process until smooth. Strain the solids through a fine-mesh sieve.
In a small bowl, whisk together the egg and egg yolks. Slowly pour in ¼ cup of the POM mixture and whisk until smooth. In a new pan, add the remaining POM mixture along with the egg mixture and cook over medium-low heat, stirring continuously until the mixture has thickened, about 8 to 10 minutes.
Remove from heat, strain through a fine-mesh sieve again, and whisk in the butter. Season with a pinch of salt and set aside to cool.
For the Garnish: Whip the whipping cream, confectioners’ sugar, vanilla, and a pinch of salt until soft peaks form.
To plate, add the POM curd to the bottom of the plate, and then add the pavlova on top. Top with more POM curd and whipped cream, and garnish with POM Arils and raspberries. Sprinkle with optional sumac.