Start by placing softened butter and granulated sugar in a mixing bowl. Beat them together until the mixture becomes light and creamy. This step creates the base of the cookie dough and helps produce a soft texture.

Add the egg, vanilla extract, and lemon juice to the bowl. Mix everything together until fully combined and smooth. The lemon juice begins adding the signature tangy lemonade flavor.

Add the flour, baking powder, baking soda, and lemon zest to the mixture. Use a spatula to gently fold them into the batter. Stop mixing when only a little flour remains visible.

Break the frozen raspberries into smaller pieces with your hands. Carefully fold them into the dough using just a few folds so the raspberries create pink streaks without fully blending into the dough.

Place the bowl of cookie dough in the refrigerator for at least 10 minutes. This step allows the dough to firm up after the raspberries release some moisture and helps the cookies keep their shape during baking.

Use a cookie scoop to portion the dough onto a parchment-lined baking sheet, leaving space between each cookie. Bake until the edges look set and slightly golden.

Allow the cookies to cool on the baking sheet before transferring them to a cooling rack. Sprinkle coarse sugar on top if desired for a sweet finishing touch.