Grits: Bring water, salt and 1 Tablespoon butter to a boil. Stir in grits and reduce heat and cook, stirring occasionally, until grits are thick and creamy, approximately 40 minutes. Remove from heat and stir in cream and remaining butter. Keep warm.
Shrimp Sauce: Saute ham and sausage in 1 teaspoon butter. Add shrimp and saute 1 to 2 minutes. Add garlic and Cajun spice. Saute 30 seconds. Add green onions and tomatoes. Add water. Finish with remaining butter. Serve over grits.