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. I usually stop when I still have some flour remnants around the bowl.
Chop or break up frozen raspberries into little pieces and lightly fold into cookie dough. You don’t want to mix too much or the juice will bleed all through the dough.
Scoop the dough into large balls, I like to use a 3 tablespoon cookie scoop for these. Place 5 cookie dough balls on your lined baking sheet. Sprinkle with flaked salt.
Bake the cookies for 12-15 minutes. You’re looking for a nice light golden brown around the edges. Let them sit on the pan after baking to finish cooking slightly in the middle.