Chocolate Pavlova With Chocolate Mousse

Preparation

1. Step 1

   Make the Pavlova: Heat oven to 250 degrees. Line a baking sheet with parchment paper and draw an 8-inch circle in the middle, then flip the paper upside down. You should still be able to see the outline.

2. Step 2

   Mix egg whites, sugar, cream of tartar and salt in a mixing bowl set over a pan of simmering water. Whisk constantly until sugar dissolves and mixture is warm, 3 to 5 minutes.

3. Step 3

   Remove from heat and, using an electric mixer, beat with the whisk attachment on medium-high speed until stiff peaks form, about 5 to 7 minutes.

4. Step 4

   Gently sift cocoa powder over the egg whites, then use a rubber spatula to fold the cocoa into the whites until just combined. A few cocoa streaks are O.K. and in fact better than overmixing, which can deflate the meringue.

5. Step 5

   Spoon half the meringue mixture onto the circle on the parchment paper to form a round, spreading it all the way to the edges. Dollop remaining meringue around the outer edges on top of the circle, creating a nest to hold the filling.

6. Step 6

   Bake for 2 hours, or until dry and firm to the touch. Turn off the oven and allow the Pavlova to cool in the oven 1 hour. Remove from oven and, if necessary, continue to cool to room temperature.

7. Step 7

   Make the mousse: In a medium saucepan, whisk together 1¼ cups/295 milliliters cream, the yolks, 3 tablespoons/35 grams sugar and the salt. Cook over medium-low heat, stirring constantly, until mixture coats the back of a spoon, 3 to 4 minutes. Remove from heat and pass through a fine-mesh strainer into a large bowl. Whisk in melted chocolate, vanilla and rum. Chill until cold, at least 2 hours.

8. Step 8

   Using an electric mixer, whisk together the remaining 1¾ cups/415 milliliters cream with remaining 3 tablespoons/35 grams sugar until firm peaks form. Stir ⅓ of the whipped cream into the chocolate mixture to lighten it, then gently fold in the remaining cream. Refrigerate, covered, at least 30 minutes or up to 3 days.

9. Step 9

   Just before serving, spoon mousse into the center of the cooled Pavlova, then top with crème fraîche. Top with fresh berries or chocolate shavings if desired.