Preheat oven to 350 degrees and line baking sheets with parchment paper or use cooking stones. Beat butter with an electric mixer on medium speed until light in color and creamy (about 5 minutes). Scrape down the sides.
Add molasses and brown sugar and mix well. Scrape down the sides again.
Add egg and vanilla. Make sure to fully incorporate (about 2-3 minutes).
In a separate bowl, mix dry ingredients: flour, baking soda, salt, spices until combined. Add dry ingredients into wet. The dough will be thick and sticky.
Remove dough and divide into 3 pieces. Cover with plastic wrap and chill for a minimum of 4 hours and overnight for best results.
Roll out dough onto slightly floured surface to a little thicker than ¼ inch. Cut into shapes and repeat the process until all dough is gone.
Bake 10-12 minutes and allow to cool on baking sheets for 5 minutes before transferring to cooling rack. Allow to fully cool before decorating.
Whisk all ingredients together in an electric mixer to desired consistency for piping.
Note: This dough MUST be chilled. The total time does not include this time.