How to Make It
Make the cookie dough: In a large bowl, whisk together the flour, baking soda, and salt.
Using an electric mixer, beat the butter and sugar until smooth. Add the egg and beat until fluffy, about 2 minutes. Beat in the vanilla.
Reduce the mixer speed to low and gradually add the flour mixture, mixing until just incorporated (the dough will be stiff). Shape into a disk. Wrap in plastic wrap and refrigerate until firm, at least 1 hour.
On a floured surface, roll the dough to ¼-inch thick. Cut out shapes using gingerbread man cutter, rerolling scraps. Place on parchment-lined baking sheets, spacing them 1½ inches apart. Rearrange legs and arms while cookies are malleable. Refrigerate 25 minutes until firm.
Preheat oven to 325 degrees. Bake until cookies are just set, about 14 minutes, rotating halfway. Cool completely on sheet pans.
Make the Royal Icing: In a large mixing bowl, beat egg whites with rubber spatula until foamy. Gradually add confectioners’ sugar and beat until icing is the consistency of toothpaste, adding additional confectioners’ sugar as needed, or water by the dropful. Divide the icing into two equal portions. Thin one half with a few drops of water to the consistency of shampoo and transfer to a piping bag fitted with a ⅛” round tip, such as an Ateco #4. Divide remaining icing into two equal portions. Transfer one half into a pastry bag fitted with a small round tip, such as an Ateco #2. Tint two-thirds of remaining icing black, adding additional confectioners’ sugar to maintain toothpaste consistency. Transfer to a piping bag with a small round tip, such as an Ateco #1. Tint remaining icing red and transfer to a piping bag fitted with a small round tip, such as an Ateco #2.
Using the thicker consistency white royal icing, pipe the outline of a voodoo doll on a cookie, then flood with the thinner white icing. Repeat with remaining cookies and set aside to dry, at least one hour or overnight. Pipe stitches on the dried white icing using the black frosting, then finish with a red royal icing heart. Set aside to dry at least 4 hours or overnight. Store in an airtight container for up to a week.