Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt. Set aside.
In a large bowl, beat the softened unsalted butter and granulated sugar together using an electric mixer on medium speed until light and fluffy, about 3 minutes.
Add the egg and vanilla extract to the butter mixture and beat until combined.
Mix in the sour cream until fully incorporated.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Scoop tablespoon-sized portions of dough and roll each into a ball.
Roll each dough ball in the additional granulated sugar to coat.
Place the dough balls onto the prepared baking sheets about 2 inches apart.
Bake in the preheated oven for 9 to 11 minutes, or until the edges are lightly golden but the centers still look soft.
Remove from the oven and allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.