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

In a large mixing bowl, combine granulated sugar and freshly zested lemon. Rub the zest into the sugar.

Add room temperature butter and brown sugar, mixing until light and fluffy, about 3-4 minutes.

Mix in one egg yolk, vanilla extract, and lemon juice until fully combined.

Gradually add salt, baking powder, baking soda, and flour, mixing just until combined.

Gently fold in the frozen raspberries.

Using a 3-tablespoon cookie scoop, place dough balls on the prepared baking sheets, spaced at least 2 inches apart.

Lightly sprinkle flaked salt on top of each cookie.

Bake for 12-15 minutes, until edges are light golden brown while centers remain soft.

Let cool slightly on the pan before transferring to a wire rack to cool completely.