Grate frozen butter and return to the fridge/freezer with shortening until ready to incorporate.
Combine flour, salt, baking powder and sift or whisk into a large bowl.
Add butter to flour mixture. Add shortening.
Carefully, quickly mix to combine. Best to mix with fork or pastry cutter so it doesn't warm.
Add a pinch of baking powder to the buttermilk and then add to mix, starting with about ¾ of the cup, adding more if needed. The dough should be very loose. Reserve the remaining buttermilk to brush tops.
Use your hands to quickly fold dough together. Use a folding action instead of a stirring. You want to work the dough as little as possible.
Flatten carefully to little over an inch thickness.
Pressingly firmly straight down, cut out biscuits. I use a 2¾" ring mold cutter.
Carefully transfer biscuits to a pan or sheet lined for baking.
Place biscuits so they are touching each other on the sides.
Optionally, brush tops with buttermilk. Sprinkle with a bit of finishingsalt, if you'd like.
Bake until golden, brush with butter, fill with jam and enjoy!
Recipe by Southern FATTY at https://www.southernfatty.com/biscuits-101/