Preheat oven to 350 degrees F. Line with parchment paper or grease 2 baking sheets.
Whisk flour, baking soda, and baking powder together in a medium size mixing bowl. Cream butter and sugar using an electric mixer in a large mixing bowl until combined, then add vanilla extract. Slowly add flour mixture until combined; be sure not to overmix.
Roll balls with approximately 2 tablespoons of the mixture and place onto baking sheets. Dip a flat-bottomed glass into the ¼ cup of sugar (in a small bowl) and firmly press down on each dough ball, until the sides come out from under the glass.
Bake for 15-18 minutes until the tops of the cookies crack. Let cool for a few minutes then move to a rack to cool before frosting.
Cream the butter with an electric mixer until smooth. Slowly beat in the confectioner’s sugar until combined, then add the vanilla extract.
Pour in the milk and continue to beat for another 3 minutes. You can add more sugar for a thicker consistency if you wish. If using color, add in and mix thoroughly.