Preheat oven to 350°F/180°C.
In a large bowl, combine butter and granulated sugar; beat with an electric mixer until creamy and well blended.
Beat in 1/2 tsp. of the orange zest, egg yolk and vanilla.
Gradually mix in flour, beating at low speed until dough is well combined.
On a lightly floured board, roll out dough about 1/8 inch thick. Cut out with floured decorative cutters about 2-in. wide.
Place cookies slightly apart on a lightly greased medium-size cookie sheet. Gather scraps of dough into a ball; reroll and cut again.
Bake cookies until pale gold all over and lightly browned at edges, about 15 minutes. Transfer to racks to cool.
In a small bowl, blend powdered sugar and orange juice until smooth.
Stir in remaining 1/2 tsp. orange zest. Spread or brush glaze over cookies; let stand until glaze is set, about 10 minutes.