This beautiful roulade makes a wonderful finale for a Valentine's Day dinner, and you could use a different design for other festive occasions. To make the decorative flourish, you simply tint a bit of the cake batter with food coloring (lemon extract is added here for flavor) and then pipe it with a pastry bag onto the parchment paper that's used to line the baking sheet; chill to set while preparing the rest of the cake batter.