1. Make the dough.
Whisk the flour, baking powder, and salt together in a medium bowl and set aside. In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the butter and sugar together on high speed until light and creamy, about 3 minutes. Add the egg and vanilla, then beat for another minute until combined. Scrape the sides and bottom of the bowl to make sure everything is mixed. Add the dry ingredients and mix on low speed until just combined. If the dough feels too sticky to roll, mix in 1 tablespoon of flour.
2. Roll and chill the dough.
Divide the dough in half. Place each portion on a piece of lightly floured parchment paper or a silicone baking mat. Roll the dough to about ¼ inch thick, adding a little more flour if it sticks. Lightly dust one piece of rolled dough with flour and place the second piece on top. Cover both tightly with plastic wrap and refrigerate for at least 2 hours or up to 2 days.
3. Cut and bake.
Preheat the oven to 350°F (177°C) and line baking sheets with parchment paper or silicone baking mats. Remove one sheet of dough from the refrigerator. Use your Milwaukee cookie cutter to cut out shapes, gathering and rerolling scraps as needed. Arrange cookies about 3 inches apart on the baking sheets. Bake for 11 to 12 minutes, or until the edges are lightly golden. Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
4. Decorate and store.
Once cooled, decorate with royal icing, easy cookie icing, or buttercream. Add food coloring if desired and allow the icing to set before serving or packaging. Store cookies tightly covered at room temperature for up to 5 days, or refrigerate for up to 10 days. If decorated with buttercream, store at room temperature for 1 day or refrigerate for up to 5 days.
