Whisk together the sugar, lemon juice and lemon zest in a large skillet. Heat over medium high heat, swirling slowly, until the sugar melts and is pale golden. Add the butter and stir until incorporated, about 30 seconds. Add the cherries, swirling the skillet to coat and bring to a boil (cherries will give off liquid and caramel will harden somewhat). Cook the cherries, stirring constantly, utnil the caramel dissolves, about 5 to 8 minutes. Pour through a fine mesh sieve set over a bowl. Return the liquid to the skillet and bring to a boil. Cook until liquid is reduced to about 3/4 cup, about 5 minutes. Remove from heat and add the cherries and Chambourd. Return to the stove and boil for 1 minute.
Spoon the warm cherry mixture over vanilla ice cream. Serve immediately.