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

In a large bowl, combine the granulated sugar and lemon zest. Use your fingers to massage the zest into the sugar—this releases the oils and intensifies the citrus aroma.

Add the room-temperature butter and brown sugar to the lemon sugar mixture. Beat with a mixer on medium-high for 3–4 minutes, until light and fluffy.

Add the egg yolk, vanilla extract, and lemon juice. Mix until fully combined and smooth.

Slowly mix in the salt, baking powder, baking soda, and flour. Mix until just combined—stop when you still see a few streaks of flour. This ensures a tender cookie.

Chop or lightly break the frozen raspberries into small chunks. Gently fold them into the dough. Be careful not to overmix, as the raspberries can bleed and turn the dough pink.

Using a 3-tablespoon cookie scoop (or a heaping spoonful), scoop dough into large balls. Place 5 balls per baking sheet to give them room to spread. Sprinkle with flaky sea salt.

Bake for 12–15 minutes, or until the edges are lightly golden. The centers may appear soft, but they’ll continue to set as they cool.

Let the cookies sit on the baking sheet for 5–10 minutes, then transfer to a wire rack to cool completely.