In a medium sauce pan over medium heat, add blueberries. Combine sugar with cornstarch and salt, then sprinkle over blueberries; add water and lemon zest to sauce pan and stir gently to combine. Bring mixture to a simmer, cooking until mixture is thickened, approx. 1 minute, stirring often. Remove from heat and let cool completely.

To assemble pies, place desired amount of prepared blueberry topping into each graham cracker crust; top with softened ice cream and smooth out each top.

Place pies onto a baking sheet and into the freezer to freeze solid.