• Sift the flour, baking powder and salt into a bowl.
  
• In a separate bowl using electric beaters or in a standing mixer, cream the butter and sugar for 3 minutes on medium to high speed until light and fluffy. 
• Add the egg and vanilla to the butter mixture and beat until incorporated.
• Turn the speed to low and slowly add the flour mixture alternating with the eggnog until the dough comes together. 
• Place the dough onto a piece of plastic wrap, parchment paper or wax paper and flatten into a round shaped disk.
• Wrap the dough disk and chill in the refrigerator until firm, at least thirty minutes to overnight.
• Once chilled, preheat oven to 325 degrees.
• Let dough sit for about 10 minutes or until soft enough to roll out.
• Using a lightly floured rolling pin, roll the dough out onto a lightly floured surface until 1/4 inch thick and even.
• Use cookie cutters to cut out desired shapes (I like to start at one end of the dough placing the cookie cutters close together).
• Using a spatula, transfer the cut-outs onto a cookie sheet (preferably a lined-silpat cookie sheet).
• Bake for 10-12 minutes for small cookies and 12-14 minutes for larger cookies rotating the sheet pan halfway through until edges turn golden.
• Cool cookies on a rack.

For the icing:

• Combine the ingredients in a bowl. 
• Use to decorate the cookies.