Place warm water (about 120 F) in a shallow bowl. Sprinkle yeast on top and wait until it becomes foamy (5-10 minutes).
In a large bowl, combine 3 ½ cups of the flour, sugar, baking powder, baking soda, salt, parsley, thyme and red pepper. Stir to combine.
Using a pastry blender, cut in the butter and shortening until it is the size of small peas.
Heat buttermilk until it is lukewarm, about 1 minute in the microwave.
Add buttermilk to the proofed yeast and mix to combine.
Add the buttermilk combination a little at a time, until you have a soft and elastic dough.
Add a little more flour if necessary, if the dough is too wet. The dough should be soft and elastic, but not sticky.
Place in a lightly greased bowl and cover with plastic wrap sprayed with non stick spray. Cover with a kitchen towel.
Leave to rest in a warm place for about 2 hours, until doubled in size.
Preheat oven to 400 F. Spray a 12” cast iron pan with non stick spray.
On a lightly floured surface, pat dough to about 1” thick.
Fold over twice into a triangle and pat to 1” thick again. Repeat.
Using a 3” biscuit cutter, cut out biscuits using an up and down motion.
Transfer to prepared pan with biscuits touching.
Repeat and pat and fold procedure with the leftover dough and cut out the remaining biscuits.
Cover with a kitchen towel and leave to rest for 15 minutes.
Combine melted butter with salt and mix to combine or use salted butter.
Brush biscuits with melted butter.
Bake for 20-25 minutes, until slightly golden.
Brush with melted butter again when you remove them from the oven.