Mix brown sugar, shortening and molasses.Stir in remaining ingredients. Cover and refrigerate at least 1 hour. Heat oven to 375 degrees.Roll dough 1/4" thick on a lightly floured cloth covered board.
Cut 3 cookies of each size with floured cutters or patterns. Place about 2 inches apart on cookie sheet.
Bake large cookies 13 minutes and small cookies 9 minutes. Cool slightly. Remove from cookie sheet. Cool completely.
Beat powdered sugar, vanilla, half and half until smooth and of spreading consistency.Assemble tree on serving plate or foil covered cardboard.
Starting with largest cookies, stack cookies as frosted or stack unfrosted cookies together with a small dab of frosting in the center of each.
Let dry or hold cookies in place with bamboo skewers if necessary.
Use remaining frosting to pipe "snow" on tree with decorating bag. Decorate with assorted candies.