01 - Whisk together flour, baking powder, and salt in a medium bowl. Set aside for later use.
02 - Beat softened butter, granulated sugar, and brown sugar in a large bowl until light and fluffy, approximately 2-3 minutes.
03 - Beat in eggs one at a time, incorporating fully before adding the next. Stir in vanilla extract and lemon zest if using.
04 - Lightly mash half the blueberries with lemon juice in a small bowl, leaving some berries whole for texture.
05 - Fold the mashed blueberry mixture into the wet ingredients until evenly distributed.
06 - Gradually fold the dry ingredients into the wet mixture, mixing just until combined. Avoid overmixing.
07 - Gently fold in the remaining whole blueberries, being careful not to crush them.
08 - Cover the dough and refrigerate for at least 1 hour until firm enough to handle.
09 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
10 - Scoop about 1.5 tablespoons of dough and roll into balls. Coat each ball generously in powdered sugar.
11 - Place sugar-coated dough balls 2 inches apart on the prepared baking sheets to allow for spreading.
12 - Bake for 11-13 minutes until edges are set and tops show characteristic crinkles.
13 - Let cookies rest on baking sheet for 5 minutes, then transfer to wire rack to cool completely.