Cup Custard

From 1911:

Three eggs beaten with three heaping table spoons of sugar, a pinch of salt, any flavoring you like and milk enough to fill four ordinary cups; after mixing with the eggs and sugar, and straining, set in a pan and half fill with boiling water.
Let bake until custard rises.
Done when a clean knife set in comes out clean.
Don’t let bake after it rises as it will whey.