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

In a large mixing bowl, combine the softened unsalted butter, granulated sugar, and powdered sugar. Beat until light and fluffy, about 3 to 5 minutes.

Blend in the vanilla extract until fully incorporated.

In a separate bowl, whisk together the all-purpose flour, salt, and baking powder.

Gradually pour the dry mixture into the butter mixture, mixing gently until combined.

Fold in any optional ingredients like lemon or orange zest, or chopped nuts or chocolate chips.

Wrap the dough in plastic wrap and refrigerate for 30 minutes.

Shape the chilled dough into small balls or a log shape.

Place the cookies on the prepared baking sheet, spacing them about an inch apart. Bake for 12 to 15 minutes, or until edges are lightly golden.

Allow cookies to cool on the baking sheet for a few minutes before transferring to a wire rack.

Optionally, dust with powdered sugar before serving.