Line 3 baking sheets with parchment paper and set aside while you prepare the cookie dough.
In a large bowl whisk together the flour, cornmeal, baking powder and salt then set aside.
Place the sugar and lemon zest in a food processor and pulse together for about 20 seconds to make a quick lemon sugar, then set aside.
In the bowl of a stand mixer or hand-held mixer, beat the 2 whole eggs, 4 egg yolks, and lemon sugar on medium-high speed for 5 minutes till thickened.
Mix in the melted butter, lemon juice and vanilla extract until combined.
Stir in the flour and cornmeal mixture until thoroughly combined.
The dough will be soft but manageable to work with.
Preheat the oven to 350 degrees F while you start rolling and shaping the S cookies.
Scoop up the cookie dough using a small ice cream scoop, approximately one and a quarter inch round.
Dust hands with flour and roll the cookie dough into a rope approximately 3¾ to 4 inches long.
Transfer the rolled dough to a parchment-lined cookie sheet and bend it into an S shape while spacing the cookies about 2 inches apart.
Beat the reserved egg whites with a fork and brush lightly over the S-shaped cookies.
Sprinkle the cookies with the turbinado sugar and bake for about 13 to 15 minutes.
When they're done, the cookies should have a lovely golden colour.
Transfer the cookies to a cooling rack.
Allow the cookies to cool before drizzling them with the melted white chocolate and topping them with finely chopped pistachios.