How to Make It
On a lightly floured work surface, roll out the dough to a rough 8-by-12-inch rectangle. Cover with plastic wrap and let rest for 25 minutes. Lightly flour the rolling pin and roll out the dough to a 14-by-18-inch rectangle. Cover with plastic wrap and let rest again for 25 minutes.
Butter a 9-inch cast-iron skillet. Flour the work surface. Roll out the dough as thinly as possible, keeping a rectangular shape. Scatter 5 slices of the butter over two-thirds of the dough and sprinkle with 1/4 cup of the sugar. Fold the bare dough into the center and fold in the opposite side, like folding a letter. Dust with flour and roll out again as thinly as possible, retaining the rectangular shape. Top with another 5 slices of butter and 1/4 cup of sugar, folding, dusting with flour and rolling out the dough again as before. Repeat the process one last time, using the remaining 6 slices of butter and 1/4 cup of the sugar, folding and rolling it out as thinly as possible.
Fold in the corners of the dough to make a slightly round shape and transfer it to the prepared skillet. With a sharp knife, make six 2-inch-long cuts all the way through the dough in a starburst pattern. Cover the dough with plastic wrap and let rise for 45 minutes. Place a baking stone or baking sheet in the lower third of the oven and preheat to 450°.
Brush the dough with the melted butter and sprinkle with the remaining 2 tablespoons of sugar. Put the skillet on the stone in the oven and bake for 25 minutes, until richly browned on top. With a spatula, transfer the cake to a large, round plate and let rest for 30 minutes. Cut into wedges and serve.