In a large bowl using an electric mixer, cream together butter, brown sugar, and molasses until fluffy, about 2 minutes. Add egg and vanilla beating until fully combined. Add zest, mixing until evenly distributed.
In a medium size mixing bowl use a whisk to sift together flour, ginger, cinnamon, baking soda, clove, salt and nutmeg. With mixer on low, gradually add dry ingredients to wet ingredients just until the dough comes together. (Don't overmix)
Divide dough in half and create two flattened discs. Wrap each in plastic wrap and chill until firm, at least 2 hours preferably 4 hours or overnight.
Preheat oven to 350° and line two large baking sheets with parchment paper. Place one disc of dough on a lightly floured surface and roll to around until 1/4-1/3" thick rectangle. Cut into 3 inch wide cookies using a gingerbread cookie cutter, Christmas trees, stars, candy canes. Transfer to baking sheets. Keep second disc chilled until ready to repeat the process.
Bake for 8-10 minutes, or until lightly puffed, adjusting the time depending on the size of the cookies.
Cool on pan for 5 minutes then transfer to a cooling rack to cool completely.
To make royal icing: Combine powdered sugar and meringue powder in a medium bowl adding 3 tablespoons of water. Beat with an electric mixer on medium speed until creamy and smooth, about 1-2 minutes. Turn to medium high speed beating until white and fluff. Add additional water, 1 teaspoon at a time, until desired consistency is reached. Likewise, if you need to thicken, add additional powdered sugar. Divide icing into 3 or 4 portions, and tint each with white, red or green gel food coloring. Decorate cookies as desired with icing, sprinkles and candy. Let dry.
Store in an airtight container at room temperature. Do not stack.