Preheat the oven to 325℉.
Sift the flour, baking powder and salt together.
Cream butter and sugar together until light and fluffy.
Add room temperature eggs, one at a time, making sure each is incorporated before adding the next.
Add the zest of 1 orange and Vanilla extract and mix. Slowly incorporate the dry ingredients, until just combined. Batter should be thick and easy to scoop with a cookie scoop.
Using a 2 inch cookie scoop, scoop cookies onto a baking sheet lined with parchment paper. Tip: Wet your finger and push down any points that are sticking up on the cookies or you can roll the cookies with a wet hand.
Bake at 325℉ for 18 mins. Wait until the cookies have completely cooled before icing.
To make the icing:Mix all of the icing ingredients and stir until the sugar has dissolved. Pro tip: Ice an entire row of cookies and then sprinkle with nonpareil sprinkles so that the colors don't bleed all over the icing.