In a medium bowl, whisk together flour, baking soda, ginger, cinnamon, cloves, nutmeg, and salt. Set aside.

In a large bowl, beat softened butter and brown sugar with an electric mixer on medium speed until light and fluffy, about 3 minutes. Add molasses, egg, and vanilla; beat until smooth, scraping down the sides as needed.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined. The dough will be soft and slightly sticky. Divide dough in half, flatten into disks, wrap tightly in plastic wrap, and refrigerate for at least 2 hours (overnight is best).

Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper. On a lightly floured surface (or between two sheets of parchment), roll one disk of dough to 1/4-inch thickness. Cut into shapes using cookie cutters. Transfer shapes to prepared baking sheets, spacing about 1 inch apart.

Bake for 8–10 minutes, until edges are just set and centers look slightly soft. Do not overbake. Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before icing.

For royal icing: In a clean bowl, combine powdered sugar and meringue powder. Add warm water and vanilla (if using). Beat on low speed until combined, then increase to medium-high and beat for 5 minutes until thick and glossy. Add corn syrup for extra sheen, if desired. Adjust consistency with additional water or powdered sugar as needed. The icing should fall from the whisk in a thick ribbon and settle into a smooth surface after about 10 seconds.

Transfer icing to a piping bag fitted with a small round tip (or use a ziplock bag with a tiny corner snipped). Pipe outlines and flood centers. Let dry at room temperature for at least 4 hours (overnight recommended). Once set, store in an airtight container with parchment between layers.