17½ ounces (500 g) unbleached all-purpose flour, plus extra for rolling out dough
1 tablespoon instant yeast
3 tablespoons sugar
1/2 teaspoon salt
1 1/4 cups (300 ml) milk, at room temperature
4 tablespoons (1/2 stick) unsalted butter, melted and cooled slightly
12 tablespoons (1½ sticks) unsalted butter, cold
1/2 cup (110 g) sugar
1 teaspoon cinnamon
1. In the bowl of a stand mixer, whisk together the flour, yeast, sugar, and salt. Add the milk and melted butter. Using the dough hook, mix at low speed for 1 to 2 minutes, or until just combined. Without removing the dough hook, cover the bowl loosely with plastic wrap and let rest for 15 to 20 minutes.
2. Uncover the bowl. Turn the speed to medium-low, and knead for about 5 minutes, or until smooth and elastic. The dough should clear the sides of the bowl and be slightly shiny but not sticky.
3. Transfer the dough into a large, lightly oiled bowl. Cover tightly with plastic wrap, and let sit at room temperature for 1 hour, or until doubled in size.
4. Turn the dough out onto a floured surface, and press to deflate. Using a floured rolling pin, roll the dough out to a rectangle about 12 x 20 inches (30 x 50 cm) in size, lifting and stretching at the corners to keep it square.
5. Using a sharp knife, cut the chilled butter into thin slices, and place evenly over 2/3 of the dough. Fold the uncovered dough over 1/3 of the butter. Then fold the remaining 1/3 over the top, making a tri-fold, like folding a letter. Pinch the edges to seal.
6. Roll the dough out again to 12 x 20 inches (30 x 50 cm), or as big as it will allow, dusting with flour as needed to prevent sticking, lifting and stretching the corners to keep it square. Tri-fold the dough again. Wrap the folded dough in plastic wrap loosely but completely, and refrigerate for at least 15 and up to 25 minutes. Lightly grease a large baking sheet or two smaller ones, or line with parchment paper. Preheat the oven to 400º F (200° C).
7. Unwrap the dough. Roll out the dough to a rectangle 15 x 30 inches (40 x 70 cm) in size, dusting with flour as needed to prevent sticking, lifting and stretching the corners to keep it square. If the dough resists, cover with plastic wrap and let rest 5 to 10 minutes.
8. Brush or spray the dough lightly with water. Mix the sugar and cinnamon together, and sprinkle evenly over the surface of the dough. Starting with one long edge, roll the dough up tightly into a log. Pinch the seam to seal the edge. Turn the log so the seam-side is down.
9. Cut the log into 1 inch (3 cm) wide pieces. Press the floured handle of a wooden spoon firmly into the top of each piece, all the way down to the counter, so that the spiraled sides flare out on either side of the handle. Transfer each piece to the prepared baking sheet. Repeat with the remaining pieces.
10. Cover loosely with plastic wrap, and let sit at room temperature for 20 minutes, or until puffy and slightly risen.
11. Bake at 400º F (200° C), in the middle of the oven, for 20 to 25 minutes, or until well-browned. Transfer to a wire rack to cool thoroughly.