Combine butter, sugar, and molasses together in a standing mixer with the paddle attachment until light and fluffy, about 3 minutes. Meanwhile, whisk together the remaining dry ingredients in a separate bowl.
Add the dry ingredients to the butter mixture in increments, and continue to beat until thoroughly mixed together.
Pour the dough out onto the countertop and divide into 4 pieces. Press each piece into a disk and wrap in plastic wrap. Place in the refrigerator and chill for 1 to 2 hours, or up to 3 days.
Adjust the racks to the center of the oven and preheat to 350 degrees F. Line sheet trays with parchment paper.
Spread 2 large pieces of parchment paper out and very lightly flour them. Place a disk of dough between the parchment sheets and roll out to 1/4-inch thickness. Repeat with the remaining disks of dough. Rework all scraps into balls and re-chill before reusing. Repeat with all the dough.
Cut out cookies and place on the parchment-lined sheet trays with an offset spatula, leaving 1-inch between each cookie. Bake the cookies for 10 to 12 minutes. Cool on the sheet tray for 5 minutes, and then transfer to a cooling rack to continue cooling to room temperature before decorating the cookies with Royal Icing.
Add ingredients to a large bowl. Beat, using a hand mixer, until glossy and stiff, about 5 to 6 minutes. Place in icing bags with fine tips to decorate cookies.