Preheat your oven to 350°F. Line a baking sheet with parchment paper and set aside.
Place the flour, ginger, baking soda, cinnamon, salt, and nutmeg into a medium bowl. Whisk until combined and set aside.
In a large bowl, beat the butter and sugar together until it's light and fluffy. Add in the egg, beating until it's fully incorporated. Add in the molasses and beat until combined.
Slowly add the flour mixture, beating on low speed or by hand, until all of the flour mixture has been completely combined into the butter mixture.
Roll the cookie dough into one-inch wide cookie balls. Roll each cookie ball in the white sugar and place on the baking sheet 2 inches apart.
Flatten each cookie with the bottom of a glass, then sprinkle with a couple of pieces of the crystallized ginger.
Bake in the preheated oven for 8-9 minutes. You want them slightly underdone; the cookies should look slightly browned on the bottom, and the tops should still be soft, denting slightly if touched.
Let them cool completely on the sheets, then remove and store layered between parchement paper in a container at room temperature for 4-5 days.