Place the butter in a large bowl and cream at high speed until fluffy. Add the sugars and beat until light and fluffy, about 3 minutes, scraping down sides of bowl occasionally. Beat in egg.

In a separate bowl, mix flour, salt and baking soda. Add to the butter mixture at low speed until just combined and add vanilla extract. Beat on medium speed, scraping bowl down, until blended. Do not overmix.

Add white chocolate chunks and mix till thoroughly combined. Refrigerate batter until cold, preferably overnight.

Preheat a conventional oven to 350 degrees or a convection oven to 300 degrees, and line several baking sheets with parchment paper. Drop heaping spoonfuls of batter 2 inches apart on the lined baking sheets and bake, turning tray once, until golden brown around edges and soft (but not bubbly), about 9 minutes in a convection oven or 12 in a conventional one. Cool on a wire rack.