In a large mixing bowl beat the butter and shortening with an electric mixer on medium to high speed about 30 seconds or until softened. Add the all-purpose flour, sugar, egg, milk, baking powder, cinnamon, nutmeg, allspice, the 1 teaspoon vanilla, and salt. Beat until thoroughly combined, scraping the sides of the bowl occasionally. Beat or stir in the whole wheat flour. Divide the dough in half. Cover and chill about 3 hours or until easy to handle.
On a lightly floured surface, roll each half of the dough to a 1/8-inch thickness. Using 2- to 3-inch cookie cutters, cut the dough into desired shapes. Place 1 inch apart on an ungreased cookie sheet.
Bake in a 375 degree F oven for 7 to 8 minutes or until the bottoms are light brown and the edges are firm. Cool on the cookie sheet for 1 minute. Remove the cookies and cool on a wire rack.
In a small bowl combine the sifted powdered sugar, the 1/2 teaspoon vanilla, and enough milk to make a frosting of drizzling or spreading consistency. Spread or pipe icing on cookies. Makes 36 to 48 cookies.