Preheat oven to 350 degrees. Line baking sheets with Silpats. Into a medium bowl, sift together flour, baking powder, baking soda, cinnamon, salt, ginger, allspice, and nutmeg; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat butter and sugar until light and fluffy. With machine running, gradually add molasses and egg. Add dry ingredients, alternating with milk, starting and ending with the dry ingredients; scrape down bowl as necessary. Stir in coconut, walnuts, and raisins.
Drop by tablespoons onto prepared baking sheets, leaving 2 inches between cookies. Bake until golden brown, 15 minutes. Remove from oven, and let cool on pans until almost, but not completely cool, about 5 minutes.
Dip tops of cookies into icing, and decorate with sprinkles or chopped nuts.