1 Preheat the oven to 275ºF (135°C). Line a baking sheet with parchment. With a sharpie or pencil and using a 9-inch pie or cake pan as a guide, trace a 9-inch (23 cm) circle on the parchment paper and then flip the paper, so the ink-side is facing down (and doesn’t touch your food), but you can still see the outline through the paper.
2 Mix the sugar and cornstarch: In a small bowl, whisk the sugar and cornstarch until combined.
3 Beat the egg whites: In the squeaky-clean bowl of an electric mixer on medium speed, slowly beat the egg whites until foamy. Sprinkle with a pinch of salt and the cream of tartar.
Continue beating just until soft peaks begin to form. With the mixer on medium speed, add the sugar 1 tablespoon at a time. When all the sugar has been added, increase the mixer speed to high and beat for 5 minutes, or until the meringue is shiny and forms stiff peaks.
Dip your index finger into the meringue and rub it between your finger and thumb. If it feels gritty, continue to beat for another 30 to 60 seconds, or until it feels perfectly smooth between your fingers and all the sugar has been dissolved.
4 Mix in the vanilla and cocoa powder: With the mixer on low speed, mix in the vanilla.
Remove the bowl from the stand and sift the cocoa powder over the meringue. With a spatula, gently fold in the cocoa powder until the mixture looks steaked with ribbons of cocoa powder. Avoid deflating the meringue.
5 Bake the meringue: Scrape the meringue into the center of the circle on the baking sheet. With the back of a large spoon, spread it into a 9-inch circle. Mound the edges slightly higher, so there’s a bowl-like indentation in the middle. Sprinkle with the almonds.
Bake at 275°F (135°C) for 30 minutes. Turn the oven down to 250ºF (120°C) and bake for another 45 to 55 minutes, or until the edges and sides look crisp and the top looks dry. It should still feel slightly soft in the center when you press it gently with your finger.
Remove from the oven and let cool completely. Transfer to a serving platter. Store at room temperature for up to 2 days, loosely wrapped in foil.
6 Top with chocolate: Preheat the oven to 350ºF. Sprinkle the chocolate over the indentation in the middle of the meringue. Place in the oven for 2 to 3 minutes, or until the chocolate melts.
With the back of a spoon or a small offset spatula, spread the chocolate across the middle of the pavlova in an even layer. Place in the freezer for 10 minutes to allow the chocolate to harden. (Make the whipped cream while you wait.)
7 Make the whipped cream: In a mixer bowl on medium speed, beat the cream, sugar and vanilla together until soft peaks form.
8 Fill and finish the pavlova: Spread the whipped cream over the top of the meringue to cover the chocolate. Arrange the raspberries on top. Sprinkle with powdered sugar. Serve immediately, or refrigerate, uncovered, for up to 3 hours.
The pavlova is best eaten on the day you serve it, but leftovers will keep for a few days, refrigerated.