Preheat your oven to 375°F (190°C) and prepare a 9x13-inch casserole dish or deep-dish pie pan by lightly greasing it.

In a large bowl, combine the diced chicken, frozen mixed vegetables, cream of chicken soup, garlic powder, onion powder, salt, pepper, and chicken broth. Stir well until all chicken pieces and vegetables are coated in the creamy mixture.

Transfer the filling to your prepared dish and spread into an even layer.

In a separate bowl, whisk together flour, baking powder, and salt. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs with pea-sized pieces.

Stir in the shredded cheddar cheese and garlic powder, then gradually add the milk. Mix just until the dough comes together, being careful not to overmix.

Drop spoonfuls of biscuit dough evenly over the chicken filling. The dough doesn't need to cover every inch, small gaps between dollops are fine and help steam escape.

Bake for 30 minutes until the biscuit topping is golden brown and the filling bubbles around the edges. The biscuits should be golden on top and a toothpick inserted into the center should come out clean. Let rest 5-10 minutes before serving.