Cornstarch (Best Option)
Use 1 tablespoon cornstarch per 1 tablespoon arrowroot powderCornstarch is a starch extracted from corn and is widely used as a thickener in savory dishes. It gelatinizes at a similar temperature to arrowroot and produces a glossy, translucent sauce, which is ideal for the creamy filling of chicken pot pie.
To use cornstarch effectively, mix it with a small amount of cold water to create a slurry before adding it to the hot filling to avoid clumping. Cook the filling for a few minutes after adding to fully activate the thickening properties.
Compared to arrowroot, cornstarch may not hold up as well if the pie is frozen and reheated multiple times, but fresh chicken pot pies will have a similarly smooth and appealing texture.