Preheat oven to 475º F. Lightly grease rimmed baking sheet pan with about a tablespoon of shortening.
Whisk together flour, sugar, and salt in a large bowl. Cut in shortening with a pastry blender or two forks. Add packet of yeast to a small glass bowl. Add warm water and allow yeast to sit for a few minutes. Pour buttermilk and yeast mixture into the dry ingredients. Stir until well combined, but do not over mix.
Dust countertop lightly with flour and turn biscuit dough out. Lightly flour the top of the biscuit dough and pat into a 1/2-inch thick circle. Cut dough into biscuits and place onto prepared baking sheet pan and place into the oven. Bake 10 - 12 minutes or until the biscuits turn a light golden brown. Remove from oven and brush the tops lightly with melted butter. Serve warm