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

In a stand mixer, cream together butter, granulated sugar, brown sugar, and salt for 4-5 minutes until light and fluffy. Add lemon zest and egg, mixing for 2 minutes before gradually adding flour and baking soda until just combined.

Scoop the dough onto prepared baking sheets, rolling each into a ball and flattening it gently for even baking.

Bake for 12 minutes until the bottoms are lightly golden. Cool completely on a wire rack.

Beat together softened butter with a pinch of salt and vanilla extract. Gradually sift in confectioners' sugar, mixing until smooth. Add raspberry powder and milk to achieve a creamy consistency.

Spread the frosting generously over the cooled cookies. Optionally decorate with extra raspberry powder or sprinkles.