Bring water and salt to a boil; stir in grits. Return to a boil, and reduce heat. Cook 4 minutes, stirring occasionally.
Combine grits and cheese in a large mixing bowl; stir until cheese melts. Combine eggs, milk, thyme, and garlic powder, mixing well. Add a small amount of hot grits mixture to egg mixture, stirring well; stir into remaining grits mixture. Add crumbled sausage, stirring well. Pour mixture into a 12- x 8- x 2-inch baking dish. Cover and refrigerate overnight.
Remove from refrigerator; let stand 15 minutes. Bake at 350° for 50 to 55 minutes. Garnish with tomato roses and parsley sprigs.
Note: Recipe may be halved; bake at 350° in a 10- x 6- x 2- inch baking dish 45 minutes.