Use a stand mixer fitted with a paddle, or handheld mixer and a large glass bowl, cream the butter until light and fluffy.
Add granulated and brown sugar to creamed butter and mix until light and fluffy. Add the egg to the bowl and mix until blended.
Pour molasses into butter mixture and beat until smooth.
In a medium bowl, whisk together the dry ingredients (flour, baking soda, cinnamon, ginger, and salt). Add the dry ingredients to the wet ingredients and mix slowly until thoroughly combined. This is a very thick dough, and you may need to use a wooden spoon or your hands to fully mix in the dry ingredients.
Shape dough into a disk, wrap in plastic wrap, and chill for at least one hour and up to 5 days. If you have chilled the dough for longer than an hour, let sit at room temperature for 20-30 minutes until the dough becomes more pliable.
Preheat oven to 350°F and line cookie sheet with parchment paper.
Place dough on a lightly floured board and roll to ¼” thick with a lightly floured rolling pin. Cut to desired shape with medium sized cookie cutters (2”-3”).
Place cut cookies on the lined cookie sheets and bake at 350 degrees for 8-10 minutes. Cool on cooling rack, then dust with powdered sugar or decorate as desired.
Storage: Molasses cookies can be stored in an airtight container on the counter, for up to one week. If the cookies are stored in stacks or layers, try putting parchment or wax paper between the layers so that the cookies don’t stick to each other.