Step 1

Preheat the oven to 400°F.

Step 2

Heat olive oil in a 9 or 10-inch cast-iron skillet over medium-high heat. Add the chicken, season with salt and pepper, and sauté until cooked through, 5 to 6 minutes. Transfer the chicken to a plate.

Step 3

Add the onion to the skillet. Sauté until tender and lightly browned, 3 to 4 minutes. Add the peas and carrots and garlic and cook 1 minute more. Sprinkle in the flour and stir until the flour dissolves. Add the chicken broth, bring to a simmer, and stir until thickened, 8 to 10 minutes. Turn off the heat, stir in the milk, and season as needed with salt and pepper.

Step 4

Add the chicken to the skillet and stir to combine. Unfold the pie crust and place over the top of the filling, tucking the excess edges inside the pan. Use a sharp knife to cut 4 (1-inch) slits in the top of the crust to vent. Bake until the crust is golden-brown, about 20 minutes.