Preheat the oven to 375°F.
In a large skillet, melt the butter over medium heat.
Stir in the flour, garlic powder, onion powder, salt, pepper, and thyme, cooking for about 1 minute until bubbly.
Gradually whisk in the chicken broth and milk, cooking until the mixture thickens, about 3-5 minutes.
Add the shredded chicken and frozen mixed vegetables to the skillet, stirring to combine.
Remove from heat and pour the mixture into a 9x13-inch baking dish.
Open the biscuit dough and separate the biscuits. Arrange the biscuits on top of the chicken mixture, leaving space between them for expansion.
Bake in the preheated oven for 25-30 minutes, or until the biscuits are golden brown and cooked through.
Let cool for a few minutes before serving.