In the Dutch oven, melt 2 tablespoons of the butter and add the milk, chicken stock, salt, hot sauce, and garlic clove. Bring to a boil over medium-high heat. Slowly whisk in the grits, cover, and bring back to a boil. Uncover, reduce heat to medium-low, and simmer, stirring occasionally until thickened, up to 1-1/2 hours. Stir in the cheese then add the butter and swirl it through the grits. Serve immediately.
