Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper for easy cleanup.

In a medium bowl, combine flour, baking powder, baking soda, and salt. Whisk these dry ingredients together until well mixed.

In a separate bowl, beat the granulated sugar and softened butter together until creamy and light.

Add the egg and vanilla extract to the butter mixture, and mix until fully combined and smooth.

Gradually fold in the dry ingredients until just combined. Be careful not to overmix.

Gently fold in the blueberries, taking care to avoid crushing them too much.

Allow the cookie dough to chill in the refrigerator for about 30 minutes.

Roll the chilled dough into balls about one tablespoon in size. Roll each ball in powdered sugar to coat it generously.

Place the powdered cookie dough balls onto the prepared baking sheet, leaving space between each to allow for spreading.

Bake in the preheated oven for 10-12 minutes, or until the cookies are set and have a slight golden edge.

Remove from the oven and let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.