Place chilled butter between 2 sheets of parchment paper; pound with a rolling pin to form a 6-inch square. Transfer butter square with parchment to refrigerator to chill.

Place bread dough on a lightly floured surface and roll into a 12- x 8-inch rectangle. Unwrap butter square, discarding parchment, and place on 1 side of dough rectangle. Sprinkle butter square with 3 tablespoons sugar. Fold 1 short side of rectangle over butter to opposite side and seal edges. Roll dough into a 20- x 8-inch rectangle on lightly floured surface. Bring both short ends of dough up and over, folding so ends meet in the middle of rectangle, and brushing off any excess flour on bottom. Fold smaller dough rectangle (about 10- x 8-inches) in half, short end to short end, creating 4 stacked layers. Wrap in plastic wrap and chill 20 minutes.

Roll stacked dough into a 20- x 8-inch rectangle on lightly floured surface. Sprinkle with 3 tablespoons of the sugar and repeat folding process. Wrap dough in plastic wrap and chill 20 minutes. Repeat rolling and folding dough process 1 more time with 3 tablespoons of the sugar. Wrap in plastic wrap and chill 20 minutes.

Brush a 9-inch cast-iron skillet with melted butter. Roll dough into a rough 9-inch circle on lightly floured surface. Place in prepared skillet and cover loosely with plastic wrap. Let rise at room temperature until slightly puffy, about 45 minutes.

Preheat oven to 425°F with the rack in the middle position. With a sharp knife, make 6 (2-inch-long) cuts all the way through the top layer of dough. Brush dough with melted butter and sprinkle with remaining 1 tablespoon sugar. Bake until top is golden brown and a wooden pick inserted in center comes out clean, 40 to 44 minutes, tenting with foil after 20 minutes if needed to prevent excessive browning. Carefully transfer hot cake to a wire rack. Let cool 30 minutes. Transfer to a platter and serve.