Preheat the oven to 350 degrees. Line a baking sheet with parchment paper.
Beat together the butter and sugar until light and fluffy, about 3 minutes with a stand mixer. Beat in the eggs and vanilla until very well combined.
In a small bowl, combine the flour, baking powder, and salt. Gradually add the flour mixture to the butter mixture and mix until combined and the dough comes together.
Use a medium cookie scoop to drop balls of dough on the prepared baking sheet, about 1-inch apart. Roll each piece of dough into a smooth ball.
Place the red sanding sugar in a small bowl and the green sanding sugar in a second small bowl. Divide the cookies into 3 sections and roll one section through the red sugar and one through the green sugar. Combine the red and green sugar and roll the remaining cookies in the sugar.
Lightly flatten the tops of the cookies and bake for 11 minutes or until edges are turning golden and tops are just slightly underdone looking.
Cool for 10 minutes on the cookie sheet before transferring to a cooling rack to cool completely.