Heat oven to 375°F. Grease a 9x13-inch baking dish.
Whisk soup, milk, onion powder, garlic powder, poultry seasoning, salt, and pepper in a large bowl.
Fold in shredded chicken and thawed vegetables until evenly coated.
Spread the mixture into the prepared dish and smooth the top.
Toss biscuit quarters with melted butter, then arrange them in a single layer over the filling.
Bake uncovered for 20 minutes, until biscuits begin to puff and the filling bubbles.
Scatter cheddar over the biscuits. Bake 8–10 minutes more, until the top is golden and cheese melts.
Rest 5 minutes. Garnish with parsley, slice into squares, and serve warm.