In a large saucepan over medium heat, add the milk, water and butter. Season with salt and white pepper. Bring the liquid to a boil. Slowly stir in the grits. Reduce the heat to medium low and continue to cook for about 1 hour or until the grits and tender and creamy, stirring every 10 minutes to prevent the grits from sticking. Add additional water during the cooking process if the liquid evaporates too much. Remove from the heat and stir in the cheese. Reseason with salt and white pepper if needed. Set aside, covered, and keep warm.

In a sauté pan, over medium heat, heat the oil. Add the sausage and render for 2 minutes. Add the garlic and sauté for 30 seconds. Season the shrimp with salt and black pepper. Add the shrimp and continue to sauté for 2 minutes. Remove the pan from the heat and add the sherry. Place the pan back over the heat and flame the sherry, shaking the pan back and fourth several times until the flame dies out. Remove the shrimp from the pan and set aside.

Add the stock and bring the liquid to a boil. Cook until the stock has reduced by two-thirds. Reduce the heat to medium low and add the butter, swirling the pan until it has melted into a rich, creamy sauce. Add the shrimp back to the sauce and cook briefly, just until the shrimp are reheated. Do not allow the sauce to boil or it will break. Remove from the heat and stir in 2 teaspoons of the parsley. To serve, spoon the grits in the center of each shallow bowl. Spoon the shrimp mixture over the grits.

Garnish with the corn relish and remaining parsley.