Direction :

1. In a large bowl, whisk together the flour salt, sugar, and instant yeast.
2. In a 2-cup liquid measure (or something similar), pour the boiling water over the buttermilk and let stand for 10 minutes. Give it a stir. The buttermilk will likely look curdled. This is okay.
3. Pour the buttermilk mixture and 4 tablespoons of the melted butter over the flour mixture. Stir until a sticky ball of dough forms. Cover the bowl with a tea towel, cloth bowl cover, or plastic wrap and set aside in a warm place to rise (see notes above) for 2 hours, or until doubled in bulk.
4. Grease a 9×13-inch baking dish. Flour a work surface and sprinkle flour lightly over the dough and around the edges. The dough will be very sticky, so use flour as needed. Gently coax the dough out of the bowl onto the floured work surface and shape into a rough ball (video guidance here) using flour as needed. Use a bench scraper to divide the ball into 4 equal portions. Shape each portion roughly into a ball, then use a bench scraper to divide each ball into 6 roughly even portions (about 45 grams each if you feel like measuring) to create 24 small pieces total.
5. Using as much flour as necessary, shape each piece roughly into a circle. It’s okay if each piece is a little misshapen. Place the dough balls into the prepared pan, spacing them evenly apart.
6. At this point, you can cover the pan and refrigerate overnight. Otherwise, heat the oven to 375ºF. Let the dough rise, uncovered, for 25 to 35 minutes, or until the dough pieces have puffed to almost fill the pan. (Note: If you refrigerate overnight, remove the pan 30 to 45 minutes prior to baking.) 
7. Transfer the pan to the oven and bake for 20-25 minutes, or until golden brown. Note: If the rolls aren’t beginning to brown after 10-15 minutes, turn the oven up to 400ºF. Remove pan from the oven and immediately brush the surfaces of the rolls with the remaining 2 tablespoons of melted butter. Sprinkle flaky salt over top to taste. Let the rolls cool in the pan for 5 minutes, then turn the pan out onto cooling racks and invert onto a plate or serving platter.
8. Serve warm with more butter on the side.