Spray the inside of a 6 quart oval slow cooker with cooking spray.
Arrange chicken in a single layer on bottom. Season with poultry seasoning, lemon pepper, garlic and salt.
In a skillet on the stovetop, cook the onion and celery with butter over medium-high heat. Cook until softened and beginning to brown, about 3-5 minutes Season with black pepper to taste.
In a medium-size mixing bowl whisk together, cream of chicken soup, cream of celery soup, chicken broth and gravy mix. Pour 3/4 evenly over chicken in crockpot.
Add the dressing mix (or stuffing mix) and cooked vegetables to remaining soup mixture. Stir to combine, then spread on top.
Cover the opening of the crockpot with doubled paper towels, then place lid firmly into place. Cook for 3-4 hours on high or 6-7 hours on low. Allow to sit uncovered for 15 minutes prior to serving. May fluff dressing with a fork, if desired.
Special Note: To prevent condensation from dripping back into the dish while cooking, cover the opening with double paper towels then lock the lid in place.
Notes
Crockpot: I prepare this chicken and dressing casserole in my 6 quart oval slow cooker. You can of course, make this in any shape slow cooker that you have.
Chicken: At the end of cooking, you can take 2 forks and gently pull apart and shred the chicken pieces or leave them whole, it's completely up to you.
Salt: Please note, there is only a small amount of added salt used to season the chicken breasts in this crockpot chicken recipe. This is due to the fact that there's ample sodium in the canned soups and the gravy mix that is poured over the chicken breasts. You can taste the sauce and and adjust the saltiness to your taste, if desired.
Protein: You can adapt this recipe using pieces of boneless turkey breast. You can also use boneless skinless chicken thighs.
Fresh Herbs: I love a splash of green for garnishing any finished dish. I used chives, but you can top this with fresh sage or parsley or omit the garnish altogether.
Use Two Boxes of Dressing Mix: If you're wondering if you can use TWO boxes of dressing mix, you can One box will result in a more moist dressing and two packages of dressing mix will stretch the servings and lend a less gravy-like sauce and consistency to the dish overall, with no other adjustments.