How to Make It
Preheat the oven to 250°. Arrange racks in the lower and middle thirds of the oven. Line 2 large baking sheets with parchment paper.
In the bowl of a standing electric mixer fitted with the whisk, beat the egg whites, cream of tartar and salt at medium speed until soft peaks form. Increase the speed to medium-high and beat in the sugar, 2 tablespoons at a time, until the meringue is stiff and glossy, about 6 minutes.
Using a large spoon, dollop 6 mounds of meringue onto each baking sheet; spread the mounds into 5-inch squares and make an impression in the center of each. Bake the meringues for 1 hour and 45 minutes, until the outsides are firm but the insides are still slightly soft; shift the pans from top to bottom and front to back halfway through baking. Transfer the baking sheets to racks and let the meringues cool completely.
In a large saucepan, combine the granulated sugar and water. Scrape the vanilla seeds onto a small plate and add the pod to the saucepan. Using a vegetable peeler, remove 2 long strips of zest from one of the oranges and add them to the pan. Halve the orange and squeeze the juice into the saucepan. Bring to a simmer, stirring until the sugar is dissolved. Add the cranberries and cook over low heat just until the berries are softened but still intact, about 8 minutes. Let cool completely. Discard the vanilla bean and orange zest and refrigerate until chilled.
Finely grate the zest of the remaining orange and transfer it to a food processor. Using a sharp knife, peel the orange, removing all of the bitter white pith. Working over the food processor, cut in between the membranes to release the orange sections into the food processor. Pulse until chopped.
In a clean bowl, using clean beaters, whip the cream, confectioners' sugar and vanilla seeds until firm. Add the chopped orange and its juice and beat just until combined.
Arrange the meringues on plates and spoon the orange whipped cream into each one. Using a slotted spoon, top with the cranberries. Drizzle with some of the juices, garnish with mint and serve right away.