<strong>Make the filling</strong>: Mix cornstarch1 1/2 and water1 1/2 together in a small bowl until combined and milky and set aside. In a medium saucepan, combine cherries12, sugar1/2, lemon juice1, and salt1/8. Stirring occasionally with a rubber spatula or wooden spoon, cook over medium heat until cherries begin to release their juices, 4 to 6 minutes. Stir in cornstarch mixture, then bring to a boil, stirring often. Once boiling, remove from heat and stir in vanilla extract1. Let cool completely.