1. Beat butter at medium speed with a heavy-duty electric stand mixer until creamy. Add 1/2 cup powdered sugar; beat at medium speed until light and fluffy. Stir in zest and juice. Whisk together flour and next 2 ingredients. Gradually add flour mixture to butter mixture, beating at low speed just until blended. Cover and chill 1 hour.
2. Preheat oven to 350°. Drop dough by level spoonfuls 2 inches apart onto parchment paper-lined baking sheets, using a 1-inch cookie scoop.
3. Bake at 350° for 13 minutes or until lightly browned around edges. Cool on baking sheets 5 minutes.
4. Toss together warm cookies and remaining 1 cup powdered sugar in a small bowl.