In a large deep saute pan over medium-high heat, add 2 tablespoons of the butter. Add the celery, onions, and garlic and cook until soft. Stir in the mushrooms, adobo sauce, poultry seasoning, wine, and chicken stock. Cook until warmed throughout, then add the bread. Turn the heat to low, and let the bread absorb the liquid. Sprinkle with the parsley and leeks, and stir to combine.
In a large saute pan, over medium-high heat, add the remaining 2 tablespoons of butter and allow it to brown. Season the chicken breasts with salt, pepper, to taste, and sprinkle with a little poultry seasoning. Sear the chicken breasts, skin side down, about 2 minutes per side. Nestle the chicken breasts into the bread mixture. Bake until an internal temperature registers 165 degrees F on an instant-read thermometer, about 20 to 25 minutes. Remove the chicken from the oven, transfer it to a serving platter and serve.