Directions
1. Combine leftover blueberries, sugar, water and lemon juice in a pot.
2. Bring to a boil and then reduce to a simmer.
3. Let simmer for 15 to 20 minutes.
4. Whisk cornstarch with equal amount of water.
5. Slowly whisk in the cornstarch mixture.
6. Remove from heat and add the vanilla extract and lemon zest.
7. Stir.
8. Once cool, serve over homemade or store-bought plain cheesecake.