Cream together butter and brown sugar in the bowl of a stand mixer, until smooth. Add molasses and egg, mixing until combined. Make sure to scrape down the sides of the bowl as needed. 

Add flour, baking soda, and spices to the bowl. Mix until everything is combined. 

Dump the dough out onto large piece of plastic wrap. Wrap the dough up and shape into a disc. Place in the refrigerator to chill for 3 hours, or overnight. 

Preheat oven to 350 degrees F when ready to bake. Line two large baking sheets with parchment paper or silicone mats. 

Roll dough out on a clean, floured work surface until it is ¼-inch thick. Cut the dough into gingerbread men. 

Add cookies to the baking sheets. You don't need to leave too much room between the cookies, but don't let them touch. 

Bake for 10 minutes, until they set. Do not over bake so they stay nice and soft. 

Cool for 5 minutes on the pan, then remove to cooling racks to cool completely.

In a large bowl, whisk all the filling ingredients together thoroughly until a thick frosting forms.

Spoon about 1 Tbsp of the cream filling on the center of a cookie and top it with another cookie, pressing down lightly to ensure that the filling spreads evenly in between but not beyond the cookie edges.

Repeat this process until all the cookies are filled.