
Preheat oven to 350 F. Line 2 baking sheets with parchment paper.
In a large mixing bowl mix together granulated sugar and lemon zest with fingers, allowing the zest to open up and become more fragrant.
Add butter and brown sugar and mix on medium-high speed for about 3-4 minutes, or until light and fluffy. Add egg yolk, vanilla and lemon juice and mix together.
Slowly mix in salt, baking powder, baking soda and flour being careful not to over mix. Stop when there are still some flour remnants around the bowl.
Chop or break up frozen raspberries into small pieces and lightly fold into cookie dough.
Scoop the dough into large balls, place 5 cookie dough balls on the lined baking sheet. Sprinkle with flaked salt.
Bake the cookies for 12-15 minutes until light golden brown around the edges.
Let them sit on the pan to finish cooking slightly in the middle.