Pit the Cherries: Remove the pits from all cherries. This is essential for a smooth, enjoyable filling (and to protect your teeth!).

Combine Ingredients: In a medium saucepan, combine the pitted cherries, sugar, salt, lemon juice, and water. Stir well.

Cook: Bring the mixture to a gentle simmer over medium heat, stirring occasionally. Let the cherries release their juices—about 5–7 minutes.

Thicken: In a small bowl, mix the cornstarch with a tablespoon of cold water to make a slurry. Slowly pour the slurry into the simmering cherries while stirring constantly.

Simmer: Continue to cook for 2–3 minutes, until the filling thickens and becomes glossy.

Finish: Remove from heat and stir in the vanilla extract. Let cool before using.