1. Make the topping: Combine cranberries, granulated sugar, and water in a saucepan. Using the tip of a paring knife, scrape vanilla seeds into pan, and toss in pod. Bring to a gentle simmer, and cook until cranberries are soft but have not burst, about 5 minutes. Let cool. Remove vanilla bean. Topping can be covered and refrigerated for up to 2 days.

2. Make the pavlova: Preheat oven to 200 degrees. Line a baking sheet with parchment paper. Using an overturned bowl or a cake pan as a guide, trace a 10-inch circle onto parchment. Turn parchment over, marked side down.

3. Beat egg whites, cornstarch, salt, and vinegar with a mixer on medium speed until foamy. Gradually add superfine sugar. Raise speed to medium-high, and beat until stiff peaks form, about 7 minutes. Reduce speed to medium, and gradually add confectioners' sugar. Raise speed to medium-high, and beat until very stiff, glossy peaks form, about 7 minutes. Beat in vanilla.

4. Using a rubber spatula or a large spoon, spread meringue into marked 10-inch circle on prepared baking sheet, forming a well in center.

5. Bake until outside is firm and bottom lifts easily off parchment, about 2 hours. (The inside should still be marshmallow soft.) Leave in a warm place to cool to prevent excessive cracking. When cool, carefully remove from parchment.

6. Before serving, whisk cream until soft peaks form. Spread in center of meringue. Spoon topping over cream.