Add 1 1/2 cups blueberries in a saucepan. Add in the water,sugar, and vanilla. Bring to a low boil over medium heat and cook until blueberries just start to break apart.

Add in the dissolved cornstarch to saucepan and bring mixture to a rolling boil. Turn heat down to a simmer and cook for 2-3 minutes or until sauce reaches desired consistency. Add additional water, one tablespoon at a time, if the sauce gets too thick.

Remove from heat. Add remaining blueberries and stir gently. Serve warm or cold. Makes 6 servings.