Combine the butter, confectioner’s sugar, and vanilla in a large mixing bowl. Slowly mix the two together until the sugar has moistened, then increase the speed and whip for another 30 seconds to combine.
Slowly stir in the flour and salt until just combined.
Shape the dough into a disk and wrap it tightly in plastic wrap. Refrigerate for 30 minutes.
Preheat the oven to 350°F (175°C).
Use a rolling pin to roll out the dough on a lightly floured surface or silicone mat. Roll to approx ¼” thickness.
Use cookie cutters to cut into the desired shapes.
Transfer the dough to a parchment-lined baking sheet.
Bake for 12-15 minutes or until the edges are slightly golden.
Let cool on the baking sheet for 5 minutes, then transfer the cookies to a wire rack to cool completely.
Icing
Whisk the confectioner’s sugar with the milk and vanilla in a medium bowl, adding more milk a little at a time until the desired consistency is achieved.
Stir in food coloring to tint the icing - if desired.
Spread or pipe onto the cooled cookies and add any sprinkles or decorations if desired before the icing hardens.