In a medium bowl, whisk the flour with the crystallized and ground ginger, baking soda and salt. Using a mixer, beat the butter with the sugar at medium speed until light and fluffy, about 3 minutes. Beat in the egg yolk and vanilla, scraping the side and bottom of the bowl. Beat in the dry ingredients at medium-low speed. Refrigerate the dough for 15 minutes.
Preheat the oven to 350 degrees. Position the racks in the upper and lower thirds of the oven. On a lightly floured surface, roll out half at a time of the dough to 1/8" thickness. Using a 2" biscuit cutter, stamp out ronds as close together as possible. Arrange the rounds on large baking sheets, about 1 inch apart. Gather the scraps and reroll, cutting out more cookies.
Bake the cookies in batches for about 20 minutes, until golden; shift the pans from top to bottom and front to back halfway through baking. Let the cookies cool on the sheets for 5 minutes, then transfer to racks to cool completely.
FOR HAZELNUT-NUTELLA SANDWICH COOKIES: In a food processor, finely grind 2/3 cup roasted and salted hazelnuts. Replace both gingers with the ground nuts. Sandwich the cookies with Nutella or another chocolate spread.
FOR COCONUT-RASPBERRY THUMBPRINTS: Replace both gingers with 3/4 cup shredded unsweetened coconut. Roll the dough into 1" balls and bake for 14 minutes. Then make a dent in the cookies and fill with raspberry jam (or any jam of your choice - muscadine is great too!). Bake for about 10 more minutes.
FOR COCOA NIB-CHOCOLATE CHIP COOKIES: Finely chop two 3-ounce milk chocolate bars with cocoa nibs. Replace both gingers with the chopped chocolate and nibs, folding them in after beating in the dry ingredients.
MAKE AHEAD: The cookie dough can be wrapped in plastic and aluminum foil and refrigerated for up to 1 week or frozen for up to 1 month. Thaw in the refrigerator before using. The baked cookies can be stored in an airtight container for up to 1 week or wrapped in plastic and foil and frozen for up to 1 month.