Preheat oven to 350 degrees and line 2 baking sheets with parchment paper or silpat mats.
In a large mixing bowl with an electric hand mixer or in the bowl of a stand mixer, cream together the softened butter and powdered sugar until smooth.
Add in the egg, molasses, and vanilla extract. Mix again until combined.
In the same bowl, add in the flour, ginger, cinnamon, nutmeg, baking powder and mix until soft dough forms.
Lightly dust a countertop and a rolling pin and roll out the cookie dough about 1/2 inch thick. Use a mini gingerbread man cookie cutter to cut out cookies and place them on prepared cookie sheet.
Bake for 6-7 minutes or until the tops no longer look glossy. Remove from oven and let cool for about 10 minutes and then transfer cookies to a cooling rack. I highly recommend placing a piece of parchment paper under the cooling rack for the icing.
Make the icing by adding the butter, oil, and milk in a microwave safe bowl and heat for 15-30 seconds or until the butter has melted. Stir in the powdered sugar and vanilla extract and mix until smooth.
Once the cookies have cooled (they can be slightly cooled), dip each gingerbread man cookie into the icing to coat the top, and then place back on the cooling rack to set for about an hour. You could also omit the icing and dust the cookies with powdered sugar. Enjoy!