Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce. Trim, peel, and finely dice carrots. Finely dice celery. Halve, peel, and dice half the onion (whole onion for 4 servings). Peel and mince garlic.

Open package of chicken and drain off any excess liquid. Heat a drizzle of oil in a medium, preferably ovenproof, pan (use a large pan for 4 servings) over medium heat. Add chicken in a single layer; season with a big pinch of salt and pepper. Cook, stirring occasionally, until browned all over, 3-5 minutes (it'll finish cooking in Step 5). Transfer chicken to a plate.

Heat a drizzle of oil in pan used for chicken over medium-high heat. Add carrots, celery, and diced onion; season with salt and pepper. Cook, stirring, until veggies are softened, 5-7 minutes. Lower heat if veggies begin to brown too quickly. Add garlic and half the dried thyme (all for 4 servings); cook until fragrant, 30 seconds.

Add 2 TBSP butter (4 TBSP for 4 servings) to pan with veggies. Once melted, stir in flour; cook for 1 minute. Add 1¼ cups water (1¾ cups for 4), stock concentrates, salt, and pepper. Bring to a boil and cook, stirring occasionally, until thickened, 3-5 minutes. Turn off heat. Stir in cream cheese until melted, then stir in chicken (add another splash of water if filling is too thick). Season with salt and pepper. If your pan isn't ovenproof, transfer filling to an 8-by-8-inch baking dish (13-by-9-inch for 4 servings).

Place 1 TBSP butter in a small microwave-safe bowl; microwave until melted, 30 seconds. Remove biscuits from package; peel apart each biscuit at the center to create two thinner biscuits. Evenly top chicken filling with biscuits, then brush with melted butter. Bake on top rack until biscuits are golden brown and chicken is cooked through, 12-15 minutes.

Let pot pie cool at least 5 minutes before serving. Divide between shallow bowls or plates and serve.