Heat the 1 tablespoon olive oil in a large pot over medium heat.
Cook the ½ cup chopped yellow onion and 1 teaspoon minced garlic until tender. Add in the 1 cup chopped celery, 2 cups cooked and shredded chicken, 1 (16-ounce) frozen bag mixed vegetables, ¾ teaspoon pepper, 1 (10.75-ounce) can condensed cream of potato soup, 1 (10.75-ounce) can condensed cream of chicken soup, and 2 cups milk.
Heat through and pour into bowls. Meanwhile, cook the Grand biscuits, if desired.
Place a cooked and warm biscuit on top of the bowl and enjoy immediately. Top with chopped fresh parsley, if desired.