In a large mixing bowl, combine melted unsalted butter, brown sugar, molasses, and vanilla extract. Add salt, cinnamon, ginger, nutmeg, and cloves. Mix until blended, then add the egg and stir until smooth.

Stir in baking soda and all-purpose flour, mixing until a soft, cohesive dough forms, adding more flour if sticky.

Divide the dough into two portions, wrap each in plastic wrap, and refrigerate for at least 30 minutes.

Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper.

Roll out one portion of chilled dough to about 1/4 inch thickness and cut with cookie cutters. Place on prepared baking sheets, spaced 1 inch apart.

Bake for 7-8 minutes until edges are lightly golden. Allow cookies to cool on sheets before transferring to wire racks.

Whisk together powdered sugar, milk, and vanilla extract until smooth. Frost cooled cookies and add decorative candies or sprinkles as desired.