Blueberry Sauce

This sauce comes from the Blueberry Breakfast Casserole, but could be used to top all kinds of desserts like ice cream or cheesecake.   Soooo delicious!  (from Confident Choices cookbook)

Ingredients:
1 C sugar
2 T cornstarch
1 C water
1 C fresh blueberries (I actually used half fresh, half frozen and as fine)
1 T unsalted butter

Directions:
Stir sugar, cornstarch, and water in small saucepan.  Cook mixture over medium heat for 5 minutes, stirring frequently.  Mixture will thicken.  Stir in blueberries and simmer the mixture, stirring frequently, about 10 minutes until berries have "burst".  Add butter and stir the sauce until butter is melted.