Preheat the oven to 325 degrees. Use
Beat the remaining butter, lemon zest, rosemary, and sugar in a bowl until light and fluffy, about 10 minutes. Beat in the egg yolks one at a time. Add the rose water, vanilla, cream of tartar, baking soda, and sour cream and mix well. Sift the remaining cup of cornmeal together with the flour and salt, and add the mixture to the batter. Mix until just incorporated.
Whip the egg whites until stiff but not dry and fold into the batter.
Bake until a thin skewer stuck in the center of the cake comes out clean, 50 to 60 minutes. Cool on a rack for 15 minutes and then unmold the cake.
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