Heat flour and butter in a small saucepan until lightly browned to make a roux. Slowly whisk in milk, making sure that no lumps form. Season to taste with salt, pepper and ground nutmeg, and continuing whisking until thickened. Set aside.
Heat olive oil in a large skillet and cook vegetables for about 5 minutes over medium high heat. Combine vegetables with white sauce and stir in chicken. Pour into a greased ovenproof baking dish.
Roll out a piece of biscuit dough to a thin (1/8 inch) layer and cut to fit over the top of the casserole dish, tucking edges down into the chicken mixture. Use a knife to create a few vents for steam to escape, then bake at 350 degrees until bubbly and biscuit crust is browned and flaky, about 20 minutes.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2011/06/chicken-pot-pie-with-herbed-biscuit-crust/