Preheat the oven to 350ºF and line cookie sheets with parchment paper.
Cream the softened butter together with the dark brown sugar and the granulated sugar until creamy.
Beat in the egg and vanilla and mix until blended.
Stir in the molasses.
In a separate bowl, combine the all-purpose flour, baking soda, salt, and spices. Stir to mix well.
Add the flour mixture to the molasses mixture until a soft dough forms.
Scoop by #30 cookie scoop (or 2 tablespoons of dough) and roll into a shallow plate of granulated sugar.
Place the cookie dough balls onto the prepared cookie sheets.
Bake for 9-11 minutes or until the edges are browned. The cookies should be soft in the center.
Allow the cookies to cool completely before icing.
To make the rum glaze:
Combine the rum and milk together in a small bowl.
Add the powdered sugar a little at a time until well combined and smooth.
Drizzle the tops of the cookies with glaze or dip the cookies into the glaze.
Allow the glaze to harden before stacking or freezing.
Notes
The rum can be substituted with milk or you can create a vanilla glaze by combining 1 cup of powdered sugar with 1 teaspoon of vanilla extract and 2 tablespoons of milk.