This was in my Mom's recipe box on one of my Grandma M's recipe cards. My Grandma M. was born in 1909, so I would say the majority of her recipes are from before 1960. The lack of directions probably dates it to earlier rather than later.
1 1/2 cup sugar
1/2 cup butter
3/4 cup milk
3/4 cup poppy seed soaked in water
2 cups flour
1 t. baking powder
4 egg whites beaten, add last