Preheat oven to 350°F/175°C. Line 2 baking sheets with parchment paper. Set aside.
In a medium bowl, sift together flour, salt, baking soda and baking powder. Set aside.
In a medium bowl, use a mixer fitted with the paddle attachment, beat butter and sugar on medium speed for 1 minute until light and fluffy. Beat in egg and vanilla extract just until combined. Scrape down the sides and up the bottom as needed. Add dry mixture and beat just until combined. Do not overmix.
Pour 1/3 cup sugar in a small bowl to make cookie coating. Using the cookie or ice cream scoop, scoop the dough out into balls and roll them in the granulated sugar before dropping them onto prepared baking sheet. Make sure to leave 2-inches space between them for spreading. Bake for 11-12 minutes until cookies begin to brown at the edges, but the center is still soft. Do not over bake. Allow cookies to cool on baking sheet for 10 minutes, then transfer to a wire rack to cool completely.
Store cookies in an airtight container for up to 3 days. The leftovers can be frozen for up to 2 months.