Easy Chicken and Dumplings

small yellow onion, minced

stalk celery, thinly sliced

carrots, peeled and diced medium

unsalted butter

all-purpose flour

chicken broth

cooked chicken, diced

green beans, trimmed and cut into 1 inch pieces

salt and pepper

For the dumplings:

all-purpose flour

baking powder

coarse salt

chopped fresh parsley

cold unsalted butter, cut into cubes

whole milk