Mocha-Berry Pavlova with Mascarpone Cream

Method

1. Preheat the oven to 300°F with the rack in the middle. Line a baking sheet with parchment paper. Using a dark marker, draw a 9-inch (23-cm) circle on the parchment by tracing around a cake pan or plate. Flip the paper over so the meringue won't touch the marker.
2. In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites and salt on medium speed until foamy and soft peaks form, about 1 minute. Increase speed to medium-high and gradually add the sugar; continue beating until stiff, glossy peaks form, 8 to 9 minutes.
3. Sift the cocoa powder into the meringue. Add the vinegar and chopped chocolate. Using a large rubber spatula, fold gently until fully combined—the mixture should be a light mocha color with no white or brown streaks.
4. Secure the parchment to the baking sheet by placing a dab of meringue under each corner. Mound the meringue onto the parchment inside the drawn circle and spread it evenly to fill the circle, smoothing the top and sides just slightly—it shouldn't be perfectly smooth. Bake for 65 to 75 minutes, until the meringue is puffed and crisp all over but still slightly wobbly in the center if touched. (Cracks are normal.) Turn off the oven, prop the door open, and let the meringue cool completely inside, at least 30 minutes.
5. Before serving, carefully peel the meringue off the parchment and transfer to a serving platter. In a medium bowl, beat the mascarpone, heavy cream, and vanilla on medium speed until just combined. Gradually add the sugar and continue beating until soft, pillowy peaks form—do not overbeat. Mound the cream onto the meringue and spread it gently, leaving a 1-inch (2.5-cm) border. Top with raspberries and sprinkle with shaved chocolate. Cut into wedges, wiping the knife between slices, and serve.