With an electric mixer, cream the butter with the sugar until the mixture is light and fluffy. Add in vanilla extract.
Add flour, baking powder and salt. Mix until it forms a dough.
Divide the dough in half. On a sheet of wax paper, form each half into an 8-inch log. Chill the logs, wrapped in the wax paper, for at least 2 hours or overnight. (If you’re pressed for time, 30 minutes in the freezer works well too!)
Heat the oven to 300°F. Line baking sheets with parchment paper.
Cut the logs into ¼-inch-thick slices with a sharp knife. Roll the slices in turbinado sugar, pressing it into the dough to coat all sides. Arrange the slices 2 inches apart on baking sheets.
Bake the cookies on the top rack of the oven for 22-26 minutes.