In A Medium Saucepan, Bring The Milk To A Boil. Stir In The Grits, And Reduce Heat To Low. Cook, Stirring Occasionally, Until Silky, About 10 Minutes. Meanwhile, Heat Olive Oil And Butter In A Skillet Over Medium Heat. Saute Onions Until Tender, Then Toss In Shrimp. Season With Salt And Pepper, And Cook 4 To 5 Minutes, Or Until Shrimp Turn Pink. Stir Shrimp Mixture Into Grits, And Continue Cooking For 10 To 15 Minutes. Serve Hot.