Preheat the oven to 325 degrees. Butter 2 (6-cup) loaf pans and line them with parchment or waxed paper.
In a mixer fitted with a whisk attachment (or using a hand mixer), cream the butter until very light and fluffy, about 10 minutes. Add the sugar and mix. Working 2 at a time, add the egg yolks, mixing well between each addition. The mixture should be very fluffy. Add the brandy, rose water, nutmeg and salt and mix to incorporate. Working in 3 batches, add the flour, mixing just until combined and scraping down the bowl between additions. In a clean dry bowl, whip the egg whites until stiff but not dry. Add to the batter and mix well, until no streaks of egg white remain. If necessary, fold in the last few streaks by hand. Pour the batter into the prepared pans and smooth the tops. Bake until golden brown and split on the top and a tester inserted in the center of the cake comes out clean (a few crumbs are okay), 70 to 80 minutes. Let cool in the pan for 30 minutes. Knock the cake out of the pan and let cool (do not remove the parchment paper; it helps the cake stay moist).
Recipe courtesy of Gale Gand, "Butter Sugar Flour Eggs" by Gale Gand, Rick Tramonto, Julia Moskin, Clarkson N. Potter Publishers, 1999