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

In a large mixing bowl, cream together softened unsalted butter and granulated sugar until light and fluffy, about 3-4 minutes.

Add the large egg, vanilla extract, lemon zest, and freshly squeezed lemon juice to the creamed mixture and mix until well combined.

In a separate bowl, whisk together all-purpose flour, baking powder, baking soda, and salt.

Gradually mix the dry ingredients into the wet ingredients until just combined, being careful not to overmix.

Gently fold in the fresh blueberries into the dough.

Scoop rounded portions of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes, until edges are golden but centers remain soft.

Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.