Whisk sugar and cornstarch together in a wide saucepan. Stir in water and orange juice; bring to a boil over medium-high heat, whisking until thickened. Stir in cherries and orange zest; return to a boil, then reduce heat, and simmer for 10 minutes. While cherries are cooking, spoon ice cream into serving bowls.

Remove cherries from heat and stir in cherry extract. Pour in brandy and ignite with a long lighter. Gently shake the pan until blue flame has extinguished itself. Spoon cherries over ice cream.