Preheat the oven to 350°F (175°C).
Shred the cooked chicken into bite-sized pieces and place in a large mixing bowl.
Add the cream of chicken soup and milk to the chicken, then sprinkle in the garlic powder, onion powder, and black pepper. Mix well.
Pour the chicken mixture into a greased 9x13-inch baking dish and spread evenly.
Separate the biscuits and cut each into quarters. Scatter over the chicken mixture.
Sprinkle shredded cheddar cheese over the top of the biscuits. Bake for 25-30 minutes until biscuits are golden brown and casserole is bubbly.
Let cool for 5 minutes before serving.