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

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

Add softened butter and brown sugar, then beat with an electric mixer on medium-high speed for 3-4 minutes until light and fluffy.

Crack an egg and separate the yolk; add it to the bowl with vanilla extract and lemon juice. Mix until incorporated.

Gradually sift in salt, baking powder, baking soda, and flour. Mix until just combined.

Fold in frozen raspberries, ensuring they are evenly distributed without overworking the dough.

Drop dough balls (about 3 tablespoons each) onto the prepared baking sheets, leaving enough space between each scoop.

Lightly sprinkle each cookie dough ball with flaked salt. Bake for 12-15 minutes until edges are golden brown.

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