Preheat your oven to 375°F. While it heats, cut the chicken tenderloins into bite-sized pieces (roughly 1.5 to 2 inches) and place them in a 9x13 inch baking dish or similar size casserole. Season the chicken pieces evenly with salt and black pepper, tossing gently to distribute the seasoning throughout.

In a mixing bowl, combine the cream of celery soup, cream of chicken soup, and milk. Stir until smooth and well combined. Add the garlic powder and mix thoroughly. I like to use a whisk to break up any lumps in the soup for a silkier sauce that coats the chicken more evenly.

Pour the creamy sauce mixture from Step 2 evenly over the seasoned chicken in the baking dish. Sprinkle the dry stuffing mix over the sauce, distributing it evenly across the top. Pour the chicken broth over the stuffing mix, making sure all of it is moistened—this allows the stuffing to absorb the liquid and become tender during baking rather than staying dry and crunchy.

Cover the casserole tightly with aluminum foil and place it in the preheated 375°F oven. Bake for 40 to 45 minutes, until the chicken is cooked through and tender. Remove the foil and bake uncovered for 5 more minutes to allow the top of the stuffing to crisp up slightly and develop a light golden color.

Remove the casserole from the oven and let it rest for 2 to 3 minutes before serving. This brief rest helps the sauce set slightly and makes serving easier. Garnish with freshly chopped parsley for a pop of color and fresh flavor that brightens the rich, creamy dish.