To Make the Sugar Cookies:

1. In a mixing bowl, combine half of the flour with the baking powder and salt. Whisk well to combine. Set aside the remaining flour for later
2. In a separate large bowl, cream the butter and sugar together using an electric hand mixer or stand mixer until light and fluffy. Add the eggs, milk, and vanilla, and beat on medium-low speed until well combined.
3. Gradually add the flour mixture (containing the baking powder and salt) to the butter mixture, mixing just until combined. Then, slowly add the remaining flour, a bit at a time, until the dough forms a smooth consistency. You may not need to add all the remaining flour; avoid adding too much, as it can make the cookies tough. The dough should but a little bit stiff and not sticky.
4. Divide the dough in half. Wrap each half in plastic wrap or place in a plastic bag, and refrigerate for 1-2 hours until firm.
5. Once chilled, preheat the oven to 400°F (200°C).
6. On a floured surface, roll out one portion of the dough to about ¼ inch thick. Dip cookie cutters in flour, then cut out shapes, placing them about 1 inch apart on an ungreased cookie sheet (using a silicone mat or parchment paper is optional).
7. Bake for 8-9 minutes, until the edges are just lightly golden. Avoid overbaking to keep the cookies soft.
8. Repeat the rolling, cutting, and baking process with the remaining dough. You can re-roll the scraps to make additional cookies. If the dough becomes too soft to handle, briefly return it to the fridge to firm up.
9. Let cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely before icing.

To Ice the Sugar Cookies:

1. In a bowl, mix the icing ingredients until smooth. Adjust the consistency as needed: add powdered sugar for a thicker consistency or milk to thin it out.
2. Divide the icing into bowls if using multiple colors, and add food coloring as desired.
3. Ice the cookies using a butter knife, icing bottle, or piping bag.
4. For best results, allow the iced cookies to dry completely before stacking, ideally overnight, to ensure the icing is fully set.