Here's a recipe for sweet potato pie from 1922
Cook 6 large sweet potatoes with a little salt
When cooked, remove from fire, peel and mash smooth.
In a separate dish, beat three eggs ~ add to the eggs, three tablespoons corn starch and a quart of good rich milk and a piece of butter the size of a walnut.
Mix well with the mashed potatoes and put in crust and bake.
A meriungue may be added if desired.