Sift or whisk together flour, ginger, nutmeg, cinnamon, salt, and baking powder; set aside.
In the bowl of your stand mixer, beat together room temperature butter, sugar, and egg until fluffy. Add molasses; mix well.
Gently mix in half of the flour mixture until smooth.
Add the rest of the flour mixture, mixing until the dough is all one color.
With your hands, shape dough into a ball and wrap in plastic wrap or parchment paper. Refrigerate 2 hours or overnight.
After the dough is chilled, preheat the oven to 375F. Lightly grease cookie sheets.
Divide dough into two parts. Return one part to the refrigerator.
On a well-floured surface, roll out dough about ⅛ inch thick.
Using your desired cookie cutters, cut out each cookie from the rolled out dough.
Using a spatula under each cookie, lift and place on prepared cookie sheets about 1 inch apart. Form the leftover dough into a ball and reroll making sure to flour the surfaces again. Repeat with remaining dough in the refrigerator.
Bake for 8 to 10 minutes, or until lightly browned.
Remove from the pan to a cooling rack until fully cool.
Make Frosting: In a small bowl, mix together confectioners’ sugar and milk with a spoon until smooth. If the frosting is too thick, add more milk.
Spread frosting over cooled cookies and decorate as desired.