Preheat your oven to 425° .
In a large bowl beat the shortening and sugar until smooth. Blend in the egg and vanilla. In a separate bowl, mix all of the dry ingredients.
Blend in the dry ingredients alternately with the sour cream. Refrigerate the dough overnight.
Roll out half of the dough on floured surface to a 12" circumference. Lift the dough off the surface and add some additional flour on the counter. Flip the dough over and continue rolling until it reaches a 3/8" thickness.
Cut with cookie cutters and carefully transfer the cookies to parchment or non-stick foil lined baking sheets. Using the scraps, roll the excess dough into a ball and repeat the process of rolling and cutting out.
Bake for 8 to 10 minutes at 425° or until VERY slightly browned on the edges. The cookies should have little to no browning as it is crucial to not over-bake them.
Allow to cool before frosting. Store in an air-tight container.
*The cookies store very well frozen in a sealed container, NOT frosted.
*Texture is best a few hours after frosting, as they soften some more.