In a large mixing bowl, cream together the unsalted butter, powdered sugar, and granulated sugar until light and fluffy.

Add the zest of 2 oranges and vanilla extract, mixing until fully incorporated.

Gradually incorporate the all-purpose flour and salt into the mixture, stirring gently until combined.

Roll the dough into a log shape, wrap tightly in plastic wrap, and chill in the refrigerator for at least 1 hour.

Preheat the oven to 350°F (175°C) and prepare a baking sheet lined with parchment paper.

Slice the chilled dough into 1/4-inch thick rounds, arrange on the baking sheet, and bake for 10-12 minutes.

Cool cookies on the baking sheet for 5 minutes, then transfer to a wire rack and dust with powdered sugar.