Preheat the oven to 350°F and bake biscuits for 7-8 minutes. Keep oven on.
In a large skillet over medium-low heat, melt 2 tablespoons butter. Add frozen veggies and stirring occasionally, cook for about 10-12 minutes, or until tender.
Add flour, parsley, and thyme and cook, stirring constantly for about 5 minutes, or until the flour coats all the veggies and starts to fry.
Whisk in chicken broth and half and half and cook until the sauce thickens.
Stir in chicken, garlic salt, and pepper. Mix until combined and cook until heated through.
Pour into a greased 9x13 baking dish and arrange biscuits on top with the baked tops facing down.
Melt remaining 2 tablespoons butter. Mix with garlic powder and brush over the tops (bottoms) of the biscuits.
Cover dish with foil and bake for 12 minutes, then remove foil and bake for an additional 10-12 minutes or until the biscuits are golden. Serve immediately.