Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened unsalted butter and powdered sugar using an electric mixer until light and fluffy.

Gradually mix in the cornstarch, all-purpose flour, and a pinch of salt, then add the lemon zest, lemon juice, and vanilla extract, mixing until a soft dough forms.

Shape the dough into 1-inch balls and place them on the prepared baking sheet, slightly flattening each ball.

Bake for 10-12 minutes until lightly golden at the edges but still soft in the middle.

Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely, then dust with powdered sugar.