In a stand mixer, combine butter and sugar and mix on medium speed until combined and light in color. Add vanilla and egg and beat again until combined.
In a medium bowl, mix together flour, clementine zest, lemon zest, salt, baking powder and baking soda.
Add dry ingredients to wet ingredients and mix until just combined.
Roll into small balls (1-2 tablespoons) and then roll in powdered sugar until coated. Place on a parchment paper lined baking sheet and bake for 9-11 minutes or until no longer shiny. Pleeeease don’t overbake these — they need to be chewy!