1. Preheat oven to 400F degrees.
2. In a large bowl, combine flour, sugar, baking powder, baking soda, cinnamon, and salt.
3. Cut in vegetable shortening using a pastry blender or a fork until mixture is crumbly.
4. Stir in raisins and buttermilk, stirring until dry ingredients are moistened.
5. Turn dough out onto a lightly floured surface and knead 3 or 4 times.
6. Roll dough to about ¾ inch thickness and cut with a 3-inch biscuit cutter or a mini biscuit cutter, and place on a parchment paper lined baking sheet.
7. Make sure not to twist the biscuits as you cut them. Just push down and then lift the biscuit up.
8. Bake for about 10-15 minutes for 3-inch biscuits and for about 6-8 minutes for mini biscuits.
9. Now for the glaze, combine powdered sugar, milk, vegetable oil and cinnamon in a small bowl.
10. Stir until completely mixed.
11. Drizzle over hot biscuits or dip the tops of the biscuits in the glaze. I like to double dip mine for a nice thick glaze on top!