Preheat the oven to 450°F. Place a cast iron skillet in the preheating oven.

In a large bowl, sift dry ingredients together. Work the shortening and butter mixture into the flour mixture with a pastry cutter until the mixture resembles coarse meal. Add the cheese and bacon and mix until incorporated. Make a well in the center of the flour mixture, then slowly pour the buttermilk, gently incorporating the buttermilk with your hands until the flour is wet. The dough isn’t going to have a form or shape at this point.

Turn the dough onto a lightly floured surface and fold on top of itself for about 1 minute. Roll or press dough to a 1/2-inch-thick rectangle and, using a biscuit cutter or cookie cutter, cut out as many rounds as possible. Gather leftover dough and roll it out to get more biscuits. Remove the skillet from the oven and transfer biscuits to the hot skillet, making sure the biscuits are touching one another. Put a light thumbprint in the middle of each biscuit to ensure they rise at the same time. Brush the top of each biscuit with buttermilk or melted butter and sprinkle with kosher salt.

Bake in the preheated oven for about 10 minutes, or until the biscuits have risen and the tops have begun to brown.