Separate out 1 cup of blueberries to cook, choosing the softest ones. Place in a saucepan with ½ cup water. Cover and bring to a boil. Separately, combine cornstarch with 2 tablespoons water. When blueberries have come to a boil, reduce heat and simmer for 3-4 minutes, until berries start to burst. Add cornstarch and remaining ingredients and cook, stirring constantly, until mixture becomes translucent, about a minute. Remove from heat and mix in the remaining blueberries. Spoon blueberry filling into pie crust. Let sit at room temperature for 2 hours to allow filling to set.
Adapted via Epicurious