Cook the biscuits as per the buttermilk biscuits recipe.
In a large saucepan melt the butter over medium heat.
Add celery and saute for 3 minutes. Add in the flour and cook, stirring constantly, for 3-4 minutes until golden and bubbling.
Whisk in the broth, milk, salt, pepper, garlic powder, and onion powder.
Bring the mixture to a rapid bubble, and then gently stir in the chicken and frozen vegetables.
Reduce the heat to low and simmer for 5 minutes.
Serve over warm, split buttermilk biscuits.