01 - Preheat oven to 300°F. Line a baking sheet with parchment paper and draw a 9-inch circle as a template on the paper.
02 - In a clean, dry bowl, beat the egg whites on medium speed until soft peaks form.
03 - Gradually add the sugar, one tablespoon at a time, beating until the meringue is thick and glossy and the sugar is completely dissolved.
04 - Sprinkle in the sifted cocoa powder, vinegar, and chopped dark chocolate. Gently fold together until just combined.
05 - Spoon the meringue onto the parchment within the drawn circle, shaping it into a nest with slightly higher edges to hold the toppings.
06 - Place in the oven and immediately reduce the temperature to 250°F. Bake for 1 hour 15 minutes. Turn off the oven, leave the door slightly ajar, and let the pavlova cool completely inside.
07 - Shortly before serving, whip the cold cream with powdered sugar and vanilla extract until soft peaks form.
08 - Gently spread the whipped cream over the cooled meringue base. Top generously with fresh raspberries and sprinkle with chocolate shavings. Serve immediately for best texture.