In a large saucepan, over medium heat, melt the butter. Stir in the sugar and cook for about 2 minutes, or until the sugar dissolves. Add the cherries, orange juice, and orange zest. Saute for 2 to 3 minutes. In a small cup, stir the cornstarch and water together to form a slurry. Stir the slurry into the cherry mixture and cook for 1 minute, until thickened. Remove the pan from the heat and pour the brandy over the cherries. Place the pan back on the heat and carefully shake the pan several times to ignite the pan. If the pan does not light, use a match to flame the cherries. Divide the ice cream between 6 shallow bowls. Spoon the cherry mixture over the ice cream and serve.