Preheat the oven to 425 degrees F. Place a heavy cast-iron skillet (preferably 12 inch) into the oven to preheat. Chill a large mixing bowl, pastry cutter, the flour and 1 stick of the butter in the freezer 15 minutes before assembling the biscuits.
Add the flour to the chilled mixing bowl. Working quickly, cut 1 stick of the butter into the flour using the chilled pastry cutter (or your fingers); the goal here is pea-size balls of butter. In batches, add in the buttermilk until the dough is cohesive yet still moist. Turn the dough out onto a floured surface and lightly press into a 1-inch-thick round. Using a 2 1/2-inch biscuit cutter or the business end of a dry measuring cup, cut out 10 biscuits. (Use the extra dough to cook up a big piece of shortcake for dessert....strawberry shortcake!)
Carefully remove the skillet from the oven and add the oil. Place the dough rounds into the hot skillet, right up against each other, and brush with the melted butter. Bake until golden brown, 15 to 25 minutes.