Make your pie crust ahead of time, so it's all set and ready to go. From that point on, there will be no baking necessary.
First, make the blueberry purée by adding around 3 cups of fresh or frozen blueberries* to a blender, blending up until smooth. Keep in mind that you may need to add more berries to obtain the desired 2 cups of finished blueberry purée.
Next, whisk together the water and corn starch in a small measuring cup. This will ensure no lumps in your pie filling.
In a medium saucepan on medium heat, whisk together the corn starch mixture with the lemon juice, sugar, and cinnamon.
Add the puréed blueberries and then the whole blueberries to the mixture. You can use fresh or frozen blueberries, but I highly recommend fresh blueberries for the whole berries.
Cook the entire mixture for about 10-15 minutes, bringing it to a slow boil, stirring constantly 'til the mixture begins to thicken.
Remove the mixture from the heat and allow it to cool completely. Sometimes I even stick it in the fridge to cool more quickly.
Meanwhile in a separate bowl, mix together the cream cheese, powdered sugar, and milk.
Spread the cream cheese filling in the cooled and prepared pie crust.
Top the cream cheese filling with the cooled blueberry pie filling.
Cover and chill the pie for at least 1-2 hours, or overnight.
Once it's chilled, you can slice it up, serve it, and enjoy! You can even top it with a dollop of Cool Whip if you want.