Preheat oven to 350°F. Line two baking sheets with parchment paper or reusable silicone baking mat. Set aside.
In a medium bowl, whisk together flour, baking soda, baking powder, and salt. Set aside.
Add butter to a large bowl. Use an electric hand mixer to beat butter until smooth. Add brown sugar and vanilla. Mix until creamy. Scrape down sides of bowl as needed.
Add in egg and beat until well combined. Add in cashew butter. Mix until smooth.
Add flour mixture to mixing bowl. Mix on low speed until there are no longer any dry streaks of flour. Alternatively, use a spatula to fold in flour. Do not overmix.
Use a 1.5 Tablespoon cookie scoop (#40 scoop) to portion out the smooth dough. Roll dough balls in granulated sugar. Then, roll in powdered sugar until well coated. Place cookie balls at least 2-inch apart on prepared baking sheet.*Don't worry if the balls are not perfect rounds. The dough will still bake into a circle.
Bake the cookies until the edges are set and the cookies are cracked on top, 15-18 minutes, rotating pans halfway through. Cool cookies in baking sheet for 3 minutes. Then, use a spatula or mini offset to transfer cookies to wire rack. Cool to room temperature.