Preheat oven to 400 degrees F (200 degrees C).
Heat olive oil in a large cast iron skillet over medium heat. Add vegetables and saute until starting to soften, about 3 minutes.
3 tablespoon Olive oil, ½ medium Onion, 1 medium Carrots, ½ stalk Celery
Add the chicken and cook until lightly browned.
1 lb Chicken
Sprinkle the flour, thyme, garlic powder, salt, and pepper over the chicken and vegetables. Stir to coat and cook for 1 minute more.
½ teaspoon Garlic powder, 1 teaspoon Salt, ½ teaspoon Black pepper, 3 tablespoon Flour, 1 teaspoon Thyme
Gradually whisk in milk until sauce is smooth. Bring to a boil, then reduce heat to low and simmer for 5 minutes.
1 cup Milk
Bring to a boil, then reduce heat to low and simmer for 5 minutes, stirring frequently so the gravy doesn't scorch.
Top with the canned, refrigerated biscuits and bake in the preheated oven for 20-25 minutes, or until the puff pastry is golden brown and the filling is bubbly. Let cool for 5 minutes before serving.
1 can Biscuits