Preheat oven to 350 degrees
Line cookie sheets with parchment paper
Sift together flour, salt, baking soda, and baking powder together
In another medium bowl, cream butter and sugar together
Add to butter/sugar; vanilla, egg, and lemon zest - stir
Add flour mixture 1 cup at a time, stir between additions
Scoop 1 inch balls onto the cookie sheets
Bake at 350 degrees for 10 minutes
Sprinkle warm cookies with a little lemon sugar
Remove to rack to cool
Serve warm and with milk