Preheat oven to 475ºF. Butter a round cake pan or skillet and set aside.
Add the flour, salt and sugar to a large mixing bowl. Cut shortening and butter into flour mixture with a pastry blender. Slowly pour milk and water into your dry ingredients and stir together until just combined. Pour the dough onto a lightly floured surface and gently pat into a rectangle about 1/2 inch thick.
For the filling
Pour melted butter on top of biscuit dough. Spread to make sure it reaches the edges of the dough.
Mix together cinnamon and sugar and sprinkle on top of melted butter. Roll the dough, beginning at the long edge, until a log of dough has been formed. Cut dough into rolls about 1 1/2 - 2 inches thick. Place slices into the buttered cake pan or skillet. Place the pan into the oven and bake for 10-12 minutes, or until lightly browned and cooked through. Do not overbake.
For the glaze
As the cinnamon roll biscuits are baking, mix together the confectioner's sugar, milk and vanilla until well combined and smooth. Remove the biscuits from the oven and allow them to cool for a few minutes and then spread the glaze over the top and serve.