Line a 10-by-15-inch jelly roll pan with plastic wrap, leaving ends out to serve as handles.

Bring 4 cups of chicken stock and 3 tablespoons of butter to a full boil over high heat. Add the grits and whisk to blend. Reduce heat to medium low to keep the grits boiling gently. Cook, whisking frequently, for 15 minutes. Add 1/2 cup of milk to the grits and continue cooking, stirring frequently, for about 15 minutes longer. Add the remaining 1/2 cup of milk, shredded cheese, and pepper. Continue cooking, stirring frequently, for 15 to 30 minutes longer; remove from the heat. Beat 1 egg lightly and then add it into to the hot grits, whisking quickly until well blended.

Place the grits back on the heat and cook for 1 minute longer. Pour the grits into the prepared pan. Cover with another sheet of plastic wrap and refrigerate until chilled and firm.

Meanwhile, prepare the creamed chicken. Heat butter in a saucepan over medium-low until melted. Add mushrooms; cook, stirring, until soft and browned. Add the sliced scallions and cook for 1 minute longer. Stir in flour until blended into the butter; stir in chicken broth. Continue cooking, stirring, until thickened. Add heavy cream and sherry. Taste and add salt and pepper as needed. Stir in chicken and pimiento, if using.

Fry grits cakes. Add oil to a large skillet, about 3 tablespoons, or coat the bottom. Heat over medium heat. Beat 1 egg in a shallow bowl. Pour cornmeal into another shallow bowl. Cut grits out with a 2 1/2 to 3-inch cutter. Dip both sides in egg then in cornmeal. Arrange the coated grits cakes in hot oil. Cook for about 3 minutes, or until browned. Turn to brown the other side.

With a slotted spatula, remove the grits cakes to a paper towel-lined plate.

Arrange 1 grits cake on a dinner plate; spoon some of the chicken mixture over it. Top with another grits cake and spoon a little more chicken mixture over that one. Sprinkle with fresh chopped parsley, if desired.