Preheat oven to 350 degrees F (180 degrees C).
Start off by mixing Unsalted Butter (150 gram) and Granulated Sugar (3/4 cup) until creamy.
Add in the Egg (1) Yolk and stir until combined.
Add the All-Purpose Flour (1 3/4 cup) and Salt (1 pinch). Mix until it comes together.
Zest the Sunkist Orange (1 1/2 tablespoon).
Add 1 Tablespoon of the Lemon Zest, Orange Zest, Lemon Juice (1/2 tablespoon), and Orange Juice (1/2 tablespoon).
Scoop out a tablespoon of dough, then roll them into balls between your hands. Place them on parchment paper. Bake for 13 minutes in your preheated oven.
Take them out before they start to brown then let them cool down for 2-3 minutes on the baking sheet before moving them on a cooling rack.
Zest the Lemon (1 1/2 tablespoon).
Prepare the icing by combining Powdered Confectioners Sugar (2 cup), the remaining Lemon Zest, Lemon Juice (1/2 teaspoon), Orange Zest (1/2 tablespoon), Orange Juice (1/2 tablespoon), Milk (1 tablespoon), and Egg White together. Whisk until you get a pourable consistency.
When cookies are completely cooled down, drizzle the top with the icing and let it stand on your counter until the icing is set. Enjoy!