Try this Yoder's Amish Chocolate Pie recipe, or contribute your own.
Starch selection dictates the final set of any custard filling, meaning direct flour-to-cornstarch swaps require careful volume adjustments to prevent a chalky mouthfeel. Standard wheat flour contains proteins that yield a cloudy appearance and a softer gel compared to pure root starches. Using all-purpose flour demands thorough cooking over medium heat to eliminate raw grain flavors before the dairy is fully incorporated.
Whisking the cocoa powder, sugar, and flour together while dry prevents stubborn lumps from forming when cold milk enters the saucepan. Medium-low heat prevents scorching at the base of thin stainless steel pots common in compact cooking spaces. Stir continuously with a flat-bottomed wooden spoon until the mixture coats the back in a thick, uniform layer that leaves a clean path when a finger is drawn through it.