Prepare the Chicken: Remove as much skin as possible from the rotisserie chicken. Reserve the skin.
Create the Fond: Add the reserved chicken skin to a pan over medium heat. Allow it to stick to the bottom of the pan to create a flavor base (fond). Once the skin has crisped up, remove it from the pan.
Sauté Aromatics: Chop the leeks and shallot. Add them to the pan along with the butter. Cook until the butter is fully melted and everything is softened, scraping up any fond from the bottom of the pan.
Add Vegetables and Herbs: Stir in the chopped carrots, fresh sage, fresh thyme, and the poultry seasoning of your choice.
Make the Roux: Add the flour to the pan and mix well to create a roux.
Deglaze the Pan: Pour in the dry white wine to deglaze the pan, scraping up any remaining fond.
Add Liquid: Gradually add the chicken stock while stirring. Allow the mixture to come back up to a boil, you should see the roux thickening the sauce. Season with salt and pepper, and stir in the aged Sherry vinegar.
Combine Chicken and Cream: Add the shredded rotisserie chicken, heavy cream, and frozen peas. Stir until well combined.
Prepare to Bake or Freeze: At this point, you can freeze the mixture for later use or pour it into a baking dish and top it with your choice of topping.
