For the cookies: Cream the granulated sugar, shortening, vanilla and orange zest thoroughly. Add the eggs and beat until light and fluffy. Add the milk and mix. Sift the flour, baking powder and salt, and then blend into the sugar mixture.
Divide the dough in half, slightly flatten between two sheets of waxed paper and refrigerate, about 1 hour (or freeze for 20 minutes).
For the egg yolk glaze: While dough is chilling, separate the eggs, reserving the whites and placing each yolk into an individual small bowl. Add 4 teaspoons water and different food coloring to each yolk and combine to make the egg yolk glaze.
Roll out the dough on a lightly floured surface. Carefully cut around hands using a dull knife.
Preheat the oven to 375 degrees F.
Transfer the hand cookies to a lightly greased cookie sheet and paint the cookies (with a soft brush) with the egg yolk glazes.
Bake the cookies, about 6 minutes. Do not allow the cookies to brown.
Transfer the cookies from the oven to a wire rack to cool.
While the cookies are cooling, make the frosting: Simply combine the powdered sugar, butter, heavy cream and vanilla in a food mixer until light and fluffy. If you like you can put the frosting in disposable piping bags to make decorating easier. Decorate the cookies with the frosting and any edible decorations, jewels, disco dust, sanding sugar you like.