Beat butter, brown sugar and molasses until light and fluffy.

Add egg and remaining ingredients and mix until combined.

Shape dough into a ball; wrap in plastic wrap and refrigerate 3-4 hours (or overnight) until firm.

Preheat oven to 350 degrees.  Grease 2 large cookie sheets.  Cut dough in half.  Roll out one half on a lightly floured surface with a floured rolling pin to about 1/4" thick. Cut out as many as possible with cookie cutters. Place on cookie sheets about one inch apart.

Repeat with the second half of the dough. Bake for 12 minutes, or until edges have become light brown.  Remove from oven and let cool on a wire rack.

Beat all ingredients on high speed until a knife drawn through the icing leaves a clean-cut path.  Divide and color with food colorings if desired.