Preheat your oven to 350°F (175°C) and prepare two baking sheets by lining them with parchment paper.

In a large mixing bowl, combine granulated sugar with the zest of a large lemon, rubbing the zest into the sugar.

Add room temperature butter and brown sugar to the bowl, beating together at medium-high speed for 3-4 minutes until light and fluffy.

Incorporate the egg yolk, vanilla extract, and fresh lemon juice, mixing until well combined.

Gradually sift in the baking powder, baking soda, and salt while slowly mixing, then add the all-purpose flour, mixing gently until just combined.

Chop the frozen raspberries into small pieces and gently fold them into the dough.

Using a cookie scoop, portion out large balls of dough onto the prepared baking sheets, spacing them out.

Sprinkle the tops with flaked salt before baking in the preheated oven for 12-15 minutes.

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