In a large bowl, gently stir together flour, baking powder, and all spices. Set aside.
In the bowl of your electric mixer (or other large bowl), beat butter until smooth. Add brown sugar, molasses, eggs and vanilla.
Gradually stir in the dry ingredients until they are fully incorporated.
Divide the dough into 3 pieces, and flatten into rounded disk (about 1 1/2 inches thick). Wrap dough in plastic wrap and refrigerate for at least 3 hours.
When dough has chilled, preheat oven to 350*F. On a lightly floured surface, roll the dough out to desired thickness (1/4- 1/2 inch thick). (The dough can be rolled out and handled just as I described in my post HERE). Cut into desired shapes with cookie cutters. Place cookies at least 1 inch apart on a baking sheet lined with parchment paper or a Silpat type liner. If the dough is too sticky or soft to work with, put it in the refrigerator or freezer for a few minutes to firm up.
Bake for 9-12 minutes (depending on the size of cookies). Cool slightly on cookie sheet, then move to a cooling rack to cool completely.
Frost with royal icing, if desire. HERE is the royal icing recipe I use, as well as some decorating tips to get you started.