butter
medium carrots, diced (about 1 1/2 cups)
stalks celery, diced (about 1 1/2 cups)
large yellow onion, diced (about 1½ cups)
chopped fresh thyme
kosher salt, divided
freshly ground black pepper
all-purpose flour
whole milk
low-sodium chicken broth
Dijon mustard
garlic powder
cooked shredded chicken
frozen peas
(16.3-ounce tube) biscuit dough