Gather all your ingredients and measure them out. Preheat your oven to 350°F (175°C), and line two baking sheets with parchment paper.

In a large mixing bowl, combine the granulated sugar and lemon zest. Use your fingers to massage the zest into the sugar.

Add the softened butter and brown sugar. Cream these ingredients on medium-high speed for about 3-4 minutes until light and fluffy.

Add the egg yolk, vanilla extract, and lemon juice. Beat on medium speed until blended.

In a separate bowl, whisk together the salt, baking powder, baking soda, and flour. Gradually add this dry mixture into the wet ingredients, mixing on low speed just until combined.

Chop the frozen raspberries into smaller pieces, and carefully fold them into the cookie dough.

Using a cookie scoop, portion out the dough onto the lined baking sheets, leaving space between the dough balls.

Sprinkle flaked salt on top of the cookie dough balls.

Bake for 12-15 minutes until lightly golden around the edges and still soft in the center.

Let the cookies sit on the pan for a few minutes before transferring to a wire rack to cool completely.