4 1/2 teaspoons (2 packages or 14 g) active yeast
3 tablespoons warm water (110 to 115°F)
5 cups (700 g) all-purpose flour
1/4 cup (50 g) white sugar
1 1/2 teaspoons kosher salt
2 teaspoons baking powder
1 teaspoons baking soda
1/2 cup (115 g) butter, cold
1/2 cup (95 g) shortening, cold
2 cups buttermilk
Extra flour for forming and cutting biscuits
3 tablespoons melted butter
Dissolve the yeast: Place the yeast and warm water in a small bowl and stir to dissolve. It should be a thick paste.
Combine dry ingredients: Place the flour, sugar, salt, baking powder, and baking soda in a large bowl. Stir together with a balloon whisk.
Add the butter and shortening: Cut the butter and shortening into 1/2-inch chunks and sprinkle over the dry ingredients. Use your fingers to smash and break the butter and shortening until they have flattened out and are about the size of peas.
Make the biscuit dough: Stir the yeast paste into the buttermilk, then add it to the biscuit dough. Don’t worry if all the yeast paste isn’t incorporated into the buttermilk. You just want to loosen it up a bit.
Stir with a large spatula until a rough dough forms. Using your hands, knead the dough a few times to make sure all the dry crumbly bits at the bottom of the bowl are incorporated.
Pat and fold the dough: Sprinkle some flour on a clean surface. Dump the dough onto the surface, and pat the dough into a rough rectangle, about 1-inch thick. Fold the dough in half and then rotate the dough 90 degrees.
Repeat this process, patting the dough into another 1-inch thick rectangle and folding it over 2 more times. Sprinkle flour under the dough if it starts to stick. Do not pat too roughly, just enough to get the dough down to 1-inch. After the final fold, pat the dough out one more time to 1-inch.
Cut out the biscuits: Dip a 2-inch round biscuit cutter in flour, then cut out biscuit rounds. Do not twist the cutter. Just press straight down as you cut. Repeat with all the dough. Gather the scraps together and cut more biscuits until you have used all the dough.
Place biscuits in skillet, then let rise for 1 hour: Brush a large 12-inch cast iron skillet with some of the melted butter. Place the biscuits in the skillet, making sure they touch slightly. If you have leftover biscuits that don’t fit in the skillet, place them in another baking pan or smaller cast iron skillet. Cover the biscuits with plastic wrap and let rise in the pan for 1 hour.
Preheat the oven: About 15 minutes before the hour is up, preheat the oven to 400°F.
Bake the biscuits: Once the biscuits are done rising, brush the remaining melted butter (you may need to microwave it for 15 seconds to re-melt it) over the top of the biscuits. Bake the biscuits for 16 to 18 minutes or until the top of the biscuits are golden brown. Let cool in the pan for 10 minutes before removing them to a cooling rack.
Serve warm with butter, honey, or your choice of jam.