In a medium bowl, combine the dry ingredients: flour, cinnamon, ginger, cloves, baking soda, and salt. Set aside.

In a stand mixer bowl—or a large bowl if using a hand mixer—beat the softened butter and brown sugar on medium-high speed until smooth and creamy. Scrape down the sides of the bowl as needed.

Add the molasses, egg, and vanilla, and beat until combined. Scrape down the sides again. Gradually add the dry ingredients to the wet ingredients, mixing on low speed after each addition. Do not overmix. Finally, stir in the milk.

Shape the dough into a ball and divide it into 4 portions. Form each portion into a 1-inch-thick disc. Wrap in plastic wrap and chill for at least 4 hours, preferably overnight.

Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.

Remove a disc from the refrigerator. Lightly flour your work surface, then sprinkle a little more flour on top of the dough. Roll the dough out to about ¼ inch thick, using gentle pressure to prevent cracking. Cut out shapes with cookie cutters. Place the cookies on the prepared baking sheet, spacing them about 2 inches apart.

Bake for 7–9 minutes, until the edges are set but the centers remain soft. Remove from the oven and let the cookies cool on the sheet for a few minutes before transferring them to a wire rack to cool completely before decorating with royal icing. For best results, bake one sheet at a time.

To make the royal icing

In a stand mixer bowl—or a large bowl if using a hand mixer—beat the egg white on low speed until foamy, about 1 minute. Continue mixing on low speed while gradually adding the powdered sugar, then add the vanilla, mixing until combined. Increase the speed to medium-high and beat until stiff peaks form. Do not overbeat, or the icing will lose its shine.

Transfer to a piping bag and decorate the cookies. For tips on achieving the perfect consistency, see the FAQ section in the post.

If you want to flood the cookies, start by outlining the edges with thicker icing and let it set slightly (2–5 minutes), then fill in the interior with thinner icing. Use a toothpick to smooth the icing. Add extra details, dots, or lines only after the icing has fully dried. Keep royal icing covered, as it dries quickly.

While the icing is still wet, you can sprinkle granulated sugar or sprinkles if desired. Let dry at room temperature. The surface will dry in 1–2 hours (complete drying takes 6–12 hours