For the Cranberry Compote
For the cranberry compote, simmer the cranberries, water, sugar and orange zest, stirring occasionally, for about 20 minutes, until the cranberries are tender and have “popped”. Remove the pot from the heat, stir in the vanilla and brandy and then cool to room temperature before chilling until ready to use.
For the Chocolate Crust
For the crust, preheat the oven to 350 F. Stir the cookie crumbs and butter together and press this into an ungreased 9-inch fluted, removable-bottom tart pan. Bake the shell for 10 minutes, and then cool.
For the White Chocolate Mousse
For the white chocolate mousse, place the white chocolate and butter in a medium bowl, with a strainer placed over it. Heat the milk to just below a simmer. In a separate bowl, whisk the yolks, sugar and cornstarch together. Whisk the hot milk into the egg mixture gradually, whisking while adding. Return this to the pot and continue to whisk over medium heat until glossy and thickened, about 4 minutes then stir in the softened gelatin. Pour this through the strainer and stir until the chocolate and butter has melted. Cool the chocolate mixture to room temperature.
Whip the cream until it holds a soft peak and fold this into the chocolate mixture. Chill the mousse until set slightly but still soft, about 90 minutes.
To assemble the tart, spread half of the mousse over the bottom of the tart shell. Stir the chilled cranberry compote to loosen it and spoon this over the centre of the tart, spreading gently. Spoon the remaining half of the mousse into a piping bag fitted with a large star tip and pipe the mousse around the edge of the tart, creating a scalloped pattern. Chill the tart until ready to serve.
The tart will keep, refrigerated, for up to 3 days.