Heat the oven to 325°F. Line a 15 x 20-inch sheet pan with parchment paper.
In a small bowl, whisk together the flour, baking soda, salt, cinnamon, nutmeg, and cloves; set aside.
In a large mixing bowl, cream the shortening and sugar until light and fluffy.
Whisk in the egg and molasses until smooth and well combined.
Add the dry ingredients and mix until fully incorporated.
Stir in the raisins.
Using about 2 tablespoons of dough, roll into balls and place on the prepared cookie sheet about 2 inches apart.
Bake for 12–15 minutes, until the edges are lightly set but centers are still soft. Remove from oven and let cool 5 minutes on the pan, then transfer to a wire rack to cool completely.
While cookies cool, whisk together powdered sugar, milk, and vanilla to make the icing.
Drizzle or spread a thin layer over the cooled cookies.