An interpretation of a recipe for "The Best Cake That Ever Was Eaten" from a 1678 manuscript by Mariabella Charles as seen in UCLA's Clark Library.
In a large mixing bowl, cream the butter, then add the sugar and blend until well mixed. In a measuring cup, measure out the cream, add the rosewater, and stir to combine. In a separate mixing bowl, combine the flour, baking powder, salt, nutmeg, and mace, and stir to combine.
Add about 1/3 of the cream mixture to the butter/sugar mixture and mix slowly. Add about 1/3 of the flour mixture and continue mixing slowly. Repeat with 1/3 of the cream mixture, 1/3 of the flour mixture, until all is combined. Carefully fold in the currants. Scoop the batter into a greased 9" x 9" square pan (or, alternatively, into a pan that has been lined with parchment paper). Bake at 350 degrees for 50 minutes, or until a toothpick inserted in the center comes out clean.