PREPARE THE PINK PAVLOVA BASE: Preheat oven to 300°F (150°C) and line a baking tray with parchment paper; draw a 7–8 inch circle as a guide. In a clean, dry bowl, beat egg whites on medium speed until soft peaks form. Add sugar one tablespoon at a time, beating until the mixture forms glossy stiff peaks. Gently fold in vinegar, cornstarch, vanilla extract, and a small drop of food coloring if using. Spoon the meringue onto the parchment, shaping into a round with high swirls and a shallow dip in the center. Reduce oven temperature to 250°F (120°C) and bake for 1 hour 15 minutes. Turn off oven and cool pavlova completely inside with the door slightly ajar.

MAKE THE RHUBARB & ROSEWATER COMPOTE: In a shallow saucepan, combine sugar and water and bring to a simmer. Add rhubarb batons and cook for 5–7 minutes until just tender but intact. Use a slotted spoon to transfer rhubarb to a plate and let cool. Stir rosewater into the remaining syrup and let cool completely. Reserve several batons and some syrup for topping. Lightly mash or chop the remaining rhubarb into a chunky compote.

WHIP THE CREAM: In a clean bowl, whip heavy cream with powdered sugar and vanilla until soft peaks form. Keep refrigerated until ready to use.

ASSEMBLE THE PAVLOVA: Place the cooled pavlova base on a serving plate. Spoon half the rhubarb compote into the center and spread gently. Top with whipped cream, then spoon remaining compote over the cream. Drizzle reserved rose syrup and finish with the reserved rhubarb batons arranged decoratively on top.