In a large mixing bowl, combine the flour, ground ginger, ground cinnamon, baking soda, ground nutmeg, and salt. In another large bowl, use an electric mixer on medium speed to beat the softened butter and brown sugar together until the mixture becomes light and fluffy. Incorporate the molasses, egg, and vanilla extract, mixing thoroughly. Gradually add the flour mixture on low speed until well blended. Form the dough into a thick, flat disk, wrap it in plastic wrap, and refrigerate for a minimum of four hours or overnight.

Preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius). On a lightly floured surface, roll out the chilled dough to a thickness of approximately ¼ inch. Utilize a 5-inch cookie cutter to cut out gingerbread men shapes, placing them one inch apart on ungreased baking sheets.

Bake the cookies for 8 to 10 minutes, or until the edges are set and just beginning to brown. Allow the cookies to cool on the baking sheets for 1 to 2 minutes before transferring them to wire racks to cool completely. Once cooled, decorate the cookies according to your preferences. Store the finished cookies in an airtight container for up to 5 days.