Preheat oven to 325ºF.
Prepare the filing by blending the cream cheese, sour cream, Truvia blend sweetener, egg and vanilla in a food processor until smooth and spun.
Pour filling into pie crust.
Bake for 15 minutes or until filling set, but not browned.
Set aside to cool.
Prepare the boysenberry topping by adding the berries, Truvia blend sweetener and water to a sauce pan on medium heat.
Use a whisk to crush berries until juices come out, but still some whole.
Heat until simmering, then mix in cornstarch and butter.
Add chia and boil.
Remove from heat and cool.
Add blueberry topping to cheesecake and enjoy!