In a bowl of a stand mixer, or a large bowl with a hand mixer, beat the butter with the powdered sugar until it's creamy (2-3 minutes).
Add in the vanilla extract and pour in the rum, give it a quick mix.
Add in the flour and spices. Using the paddle attachment, mix until the dough is well combined. Scrape the sides of the bowl using a rubber spatula to ensure you are getting all of the ingredients mixed in the batter.
Roll the dough into a small log shape, about 1 ¼- 1 ½ inch in diameter. Wrap in Saran Wrap and refrigerate for 1-3 hours, or place in the freezer for 30 minutes.
Once you remove it from the freezer or refrigerator, Preheat the oven to 350°F/180°C.
While the oven is heating, carefully slice the cookies into small discs, about ¼-inch thick. Place them 1-inch apart on ungreased baking sheets.
Bake for about 12-15 minutes or until set. Remove from the oven to wire racks to cool.
Once cooled, coat the cookies with the remaining powdered sugar and top with sprinkles, crushed peppermint, or melted chocolate.