My Dad's mom would make this for him every time we visited Illinois. As a child, I could hardly wait for the filling to cool enough to eat. The secret is to stir constantly for a rich, velvety smooth pudding-like melt-in-your-mouth experience. These instructions are per my grandmother, written down by my mother not too long before Grandma passed away. Grandma wouldn't give the recipe away until her last years. It's a family treasure now! Top the pie with meringue, whipped cream, or whipped topping.