To cook the chicken:
Place the chicken in a medium saucepan and cover with cold water. Add the chicken base, the vinegar, sugar, kosher salt and black pepper. Bring to a gentle simmer over medium heat. Cook for 30 minutes then remove from the heat and let the chicken continue “cooking” in the poaching liquid for 15 minutes.
Transfer the chicken to a bowl or platter until cool enough to handle. Remove the meat from the bone and discard the skin of the chicken. Shred into bite size chunks.
For the sauce:
Melt the butter in a large skillet over medium heat. Add the onions, the celery and the carrots, cooking until the vegetables are tender, about 12 to 15 minutes.
Stir in the kosher salt, black pepper and Worcestershire sauce.
Add the flour, mixing into the vegetables. Continue cooking over medium heat for about 3 minutes stirring frequently.
Pour the milk into the vegetables, stirring until you have a smooth sauce. Reduce the heat to medium low and continue cooking until the sauce has thickened.
Toss in the peas and the chicken, mixing to coat evenly with the sauce.
For the cornbread pancakes:
Combine the cornbread mix with the kosher salt, black pepper, sage, and parsley.
Whisk together the buttermilk with the egg and 2 tablespoons of the melted butter. Pour the buttermilk mixture into the cornbread mix and whisk to blend.
Heat a griddle to medium heat and lightly brush with some of the remaining melted butter. Ladle or scoop the batter onto the griddle and cook until golden, about 3 to 5 minutes per side.
To serve:
Spoon the hot creamed chicken sauce over the warm cornbread pancakes.