In a large bowl, combine flour, baking powder, sugar, cinnamon and salt. Cut in shortening until mixture resembles coarse crumbs. Add milk and raisins; stir just until combined.
Turn dough onto a floured surface. Knead just until smooth, about 2 minutes. Roll to 1/2-in. thickness. Cut with a floured 2-1/2-in. round biscuit cutter; place on an ungreased baking sheet. Bake at 450° for 12-15 minutes or until golden.
Meanwhile, combine icing ingredients. Drizzle over warm biscuits.