First, proof the yeast by add warm water and sugar to a glass measuring cup or bowl.
Stir in the yeast.
Let yeast proof while moving on the next step.
In a large bowl, sift or whisk together sugar, flour, baking powder, baking soda, salt.
Using a pastry cutter, cut in butter and shortening until mixture resembles small crumbs.
Make a well in the center of the bowl and pour in the yeast mixture and buttermilk, stirring to combine just the yeast and buttermilk.
Next begin pushing the flour mixture into the well, until everything is combined and a dough has formed.
Lightly flour a work surface and turn the dough out on the work surface.
Gently knead the dough to incorporate all the crumbs until you have a mound of soft, pliable dough.
Fold the dough several times (this will create layers in your finished biscuits.)
Pat the dough out into a 1-inch thick rectangle.
Using a floured 2.5 inch round biscuit cutter, cut out 8-10 biscuits. (do not twist the cutter, simply go straight down and pull up)
Place biscuits on a lightly greased pan, about 1/2 inch apart. ( My 9-inch pan held 8 biscuits)
Cover pan loosely with plastic wrap and place in a very warm, draft-free location. (I put mine in the oven with just the pilot light on)
Let rise for 1-hour and then preheat oven to 400 F.
Remove plastic wrap and gently brush the tops with a light coating of heavy whipping cream. (This will help with browning)
Bake for 10-12 minutes. (check on it at the 8-minute mark) Turn the oven to a low broil during the last minute to create golden tops (be sure to watch it constantly while broiling to prevent burning)
Brush with melted butter as soon as they come out of the oven.