German Puffs

From 1915:

By May Busch
To make German puffs it is necessary to have the following ingredients: 2 oz. of butter, 3 tablespoons of sugar, 3 eggs, whites and yolks separated, 3 teacups of milk, 3 teacups of flour, 1 saltspoonful of salt, and a few drops of vanilla.
First beat the butter to a cream.
Then add the sugar and well-beaten yolks, and the milk, which should be salted.
Dredge in the flour by degrees.
When these are all well-mixed, add the flavoring and the whites of the eggs, which must have been previously beaten to a stiff froth; bake the whole in well-buttered teacups about 15 or 20 minutes until they are a nice light brown.
Serve immediately with a nice sweet sauce. Inasmuch as these puffs rise a great deal be sure not to fill the teacups to the top.