No-Fuss Biscuit-Topped Chicken Pot Pies

NO FUSS BISCUIT-TOPPED CHICKEN POT PIES2 ½ c. chicken stock3 medium carrots, peeled and finely chopped3 medium Yukon God potatoes, peeled and finely chopped1 stalk celery, finely chopped4 T. butter1 large Vidalia onion, finely chopped1 (8-oz.) carton cremini mushrooms, finely…