Preheat the oven to 375°F (190°C).

In a large bowl, combine the diced chicken, frozen mixed vegetables, cream of chicken soup, 1 teaspoon garlic powder, onion powder, salt, pepper, and chicken broth. Mix until everything is evenly coated.

Spread the filling into a 9x13-inch casserole dish in an even layer.

In a separate bowl, whisk together the flour, baking powder, and 1 teaspoon salt.

Add the cold cubed butter to the flour mixture and cut it in with a pastry cutter or two forks until the mixture resembles coarse crumbs.

Stir in the shredded cheddar cheese and 1 tablespoon garlic powder for the biscuit dough.

Pour the milk into the flour mixture gradually, stirring just until the dough comes together. Stop as soon as it’s combined; do not overmix.

Drop spoonfuls of the biscuit dough across the chicken filling, spacing them so they’ll bake into a somewhat connected topping.

Bake for about 30 minutes, until the biscuit topping is golden brown and the filling is bubbling at the edges.

Let the casserole rest for a few minutes before serving so the filling sets slightly.