Make the blueberry puree by cooking blueberries in a small saucepan over medium heat until they burst and release juices, about 5-7 minutes. Remove from heat and cool.

In a mixing bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy.

Incorporate the egg, vanilla extract, and cooled blueberry puree into the creamed mixture.

In another bowl, whisk together flour, baking powder, and salt. Gradually add the dry mixture to the wet mixture, mixing gently until just combined.

Wrap the dough in plastic or place in an airtight container and chill in the refrigerator for at least one hour.

Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.

Scoop chilled dough into balls (about 1 tablespoon each) and roll in powdered sugar.

Place on lined baking sheets with spacing for spreading, and bake for 10-12 minutes until crinkly and slightly golden.

Allow to cool on the baking sheet for a few minutes before transferring to a wire rack.