Crust: Grease a 25cm pie dish with butter or nonstick spray. Mix all the ingredients for the crust and press into the bottom and up the sides of the pie dish and chill.
Filling: Heat the milk, cocoa powder and brown sugar together over medium heat until the sugar has dissolved. Blend the cornflower with a little cold milk to form a smooth paste and stir into the milk mixture. Bring to boil while stirring.
Simmer for a few minutes or until the mixture thickens and is done. Remove from the heat. Mix the chocolate liqueur and gelatin and stir into the hot mixture. Pour into the pie crust and leave to cool.
Drain the pears and pour the syrup into a small saucepan. Boil rapidly until reduced by half. Remove from the heat and add the chocolate pieces, stirring until melted. If necessary return to the heat to allow the chocolate to melt, but don't allow to boil. Cool slightly.
Arrange the pears, cut sides facing down, on the cooled chocolate filling in the pie crust and pour over the cooled sauce.
Chill. The sauce will run down the sides of the slices when you cut the tart. Serve with whipped cream and decorate with chocolate curls if desired.
Makes 1 large tart.