Mix together the sugar and cornstarch in a medium sized saucepan until well combined.
Add in the blueberries, water, lemon juice and vanilla extract to the saucepan and stir.
Cook the blueberry mixture over medium to medium-high heat, stirring often, until the liquid has reduced and thickened to your desired consistency. The nature should be gently bubbling continuously.
Remove from the heat and allow to fully cool before storing or using for a recipe. Enjoy!
Notes
Fresh or frozen blueberries can be used.
Arrowroot can be substituted for the cornstarch.
This recipe makes 2 cups of pie filling. If you want to make a pie using this filling, you'll need to make a double batch of this recipe.
This can be used as an acre cream topping or other dessert topping (like cheesecake) or even in oatmeal!