Prepare the flax egg and set it aside.
Mix Dry Ingredients: Combine flour, baking soda, baking powder, cinnamon, ginger, and salt in a medium bowl and stir until combined.
Using a hand-held or stand mixer with a paddle attachment, beat the butter with the granulated and brown sugars in a mixing bowl. Beat for 1 to 2 minutes, until light and fluffy. Add the molasses and beat again until combined. Add the flax egg and beat for another minute until combined. Be sure to scrape down the sides of the bowl as needed while beating.
Add the dry ingredients and beat at low speed until it forms into a dough. Cover and refrigerate the dough for 1 to 24 hours.
When you're ready to bake the cookies, preheat your oven to 350°F. Line a cookie sheet with parchment paper or use silicone baking mats.
Roll dough into balls, approximately the size of a tablespoon. I like using a cookie dough scoop to keep the balls the same size. Roll the cookie dough balls in sugar.
Place prepared balls on a cookie sheet, at least 2 inches apart. Bake 8 to 10 minutes, until the cookies are firm and beginning to brown. When they're done, allow the cookies to cool for 2 to 3 minutes on the cookie sheet before transferring to a wire rack to cool completely.
Store in an airtight container at room temperature for 1 week. Cookies can also be stored in the fridge. They can be frozen for up to 2 months.