Heat oil in a Dutch oven over medium-high heat.

Sauté celery, carrots, and onion in oil for about 7 minutes, until crisp-tender.

Add chicken broth, cream of chicken soup, and pepper to the Dutch oven; bring to a boil.

Reduce heat to low; stir in cubed chicken and bring to a simmer.

In a separate bowl, stir together biscuit baking mix and milk.

Drop the batter by tablespoonfuls into the simmering broth.

Cover and cook over low heat for 15 minutes without lifting the lid.

Serve the fluffy chicken and dumplings for a comforting meal.