Preheat oven to 400 degrees F. Line a baking sheet with parchment paper.
Combine yeast and water and let it stand until foamy.
Mix the flour, sugar, baking powder, baking soda and salt in a large mixing bowl.Scatter the shortening and butter over the dry mixture, and with a pastry cutter (or your fingers), cut the fat into the flour mixture until crumbly.
Add the yeast mixture and butter milk and stir until ingredients are moistened and everything is blended — but don’t over-do it on the mixing.
Put the dough under the dough hook of a stand mixer or onto a floured surface and knead for 1 minute.
Roll dough to about 1/2 inch thickness and cut into 2 inch circles.Arrange circles on baking sheet and bake for 12 to 15 minutes or until golden.