Peel shrimp, and devein, if desired.
Bring 3 cups water, cream, butter, and salt to a boil in a large saucepan over medium-high heat. Reduce heat to medium, and whisk in grits. Cook, whisking constantly, 7 to 8 minutes or until mixture is smooth. Stir in 1 pound shrimp, cheese, and garlic, and cook 1 to 2 minutes or until thoroughly heated. Garnish, if desired.