Preheat oven to 400 degrees and place a cast iron skillet in the oven to preheat.
Place the flour in a food processor. Cut butter into small cubes and sprinkle over butter. Cover food processor and pulse in short bursts until butter pieces are about the size of peas. Transfer mixture to a large bowl. Add buttermilk and stir gently until just combined.
Place biscuit dough on a well floured surface and gently pat or roll out to 1-inch thickness. Sprinkle with cinnamon sugar mixture. Fold dough in half and pat flat. Sprinkle with cinnamon sugar. Fold in half and roll out to 1 inch thickness.
Remove the skillet from the oven and a little olive oil, just enough to coat the bottom of the pan.
Using a biscuit cutter (I used a 2-inch cutter), cut biscuits from dough and place biscuits in the skillet. Start by placing them around the outside and then fill in the middle. Combine biscuits scraps, roll out one more time, cut out biscuits. (You could probably roll it out one more time if you need to, but the dough will probably too overworked after that.)
Brush melted butter over the tops of the biscuits and bake for 25 minutes, or until tops are golden brown. Remove from oven and let cool.