Beat the 6 egg whites and salt with an electric mixer until soft peaks form. Add half of the sugar and beat until stiff, glossy peaks are formed.
In a separate bowl, beat the egg yolks and remaining sugar with an electric mixer until pale and doubled in volume. Gradually add the vanilla extract, rose water and butter and mix until well combined.
Add the flour to the batter in 2 additions, alternating with the egg whites. Dye the batter pale pink and gently fold to combine.
Pour the batter into the swiss roll cake pan, on top of the pattern. Gently smooth the surface and bake at 350F for 13-15 minutes, until the edges are golden.
Dust a large sheet of wax paper with confectioner’s sugar. As soon as the cake comes out of the oven, invert it onto the wax paper. Peel off the top layer of parchment paper, place another layer of wax paper on top, then invert again, so that the patterned side is facing down. Remove the wax paper and starting at one long end, gently roll the cake up. Wrap in a kitchen towel and cool completely.