Step 1

To make the dough, in a stand mixer with the dough hook, mix both flours, the sugar, yeast, cardamom and salt on low until combined, about 30 seconds. In a liquid measuring cup or small bowl, combine the milk and butter. With the mixer running on low, gradually add the milk mixture to the dry ingredients, followed by the egg yolk. Mix on low until the ingredients form a rough, sticky dough, 2 to 3 minutes.

Step 2

Increase to medium-low and knead until the dough is smooth and elastic and pulls away cleanly from the sides of the bowl, about 20 minutes. The dough should be supple and soft to the touch; it also will feel warm.

Step 3

Mist a 9-by-13-inch baking dish with cooking spray. Scrape the dough into the baking dish and press it with your hands to flatten it into an even layer that is as thin as possible. Cover with plastic wrap and let rise at room temperature until just shy of doubled in size, about 1 hour. Transfer to the refrigerator and chill for at least 2 hours or up to 24 hours.

Step 4

When you are ready to fill, shape and bake the buns, make the filling. In a medium bowl, mash together butter, brown sugar and cardamom until well combined; set aside. Line 2 rimmed baking sheets with kitchen parchment.

Step 5

Lightly flour the counter and turn the chilled dough out onto it with a short end nearest you; try to maintain the rectangular shape. Lightly dust the dough with flour and roll it into a 12-by-16-inch rectangle of even thickness, occasionally flipping the dough to ensure it is not sticking. Spread the filling in an even layer on the dough, all the way to the edges. Fold the top third of the dough down over itself, then fold the bottom third up. Rotate the dough so a short side is nearest you and roll the dough once again into a 12-by-16-inch rectangle of even thickness.

Step 6

Rotate the rectangle so a long side is parallel with the counter’s edge. Using a metal bench scraper or pizza wheel, trim the short sides to create straight lines; discard the scraps. Cut the dough crosswise into 16 even strips.

Step 7

Pick up one strip by the ends and gently stretch it to about 16 inches by gently “bouncing” it against the counter while very gently pulling on the ends.

Step 8

Twist the ends of the strip in opposing directions while gently stretching it to create a loose spiral about 16 inches long.

Step 9

Holding it in place between your thumb and your index, middle and ring fingers, wrap the strip around your fingers.

Step 10

Fully wrap the strip around your index, middle and ring fingers without untwisting the spiral.

Step 11

Tuck the end under and up into the center while sliding out your fingers to create a turban-shaped knot. Pinch the center of the bottom of the bun to seal so the coil does not unwind during baking. Place on one of the prepared baking sheets.

Step 12

Shape the remaining dough strips in the same way, arranging 8 buns on each baking sheet, placing them in 2 outer rows of 3 and an inner row of 2, for staggered spacing. Drape a kitchen towel over each baking sheet or cover lightly with plastic wrap and let rise until the buns are nearly doubled in size, 45 minutes to 1½ hours (timing depends on the temperature of the dough as well as the ambient temperature in the room).

Step 13

While the buns are rising, heat the oven to 400°F with a rack in the middle position. In a small bowl, use a fork to beat the reserved egg white with 1 tablespoon water.

Step 14

When the buns are nearly doubled in size, lightly brush each on the first baking sheet with egg white, then sprinkle with half of the white sugar. Bake until the buns are deep golden brown, 15 to 18 minutes; it is normal for some filling to seep out and caramelize on the baking sheet. Meanwhile, brush the remaining buns with egg white and sprinkle with the remaining white sugar.

Step 15

When the buns are done, cool on the baking sheet on a wire rack. Bake the buns on the second baking sheet in the same manner. Serve slightly warm or at room temperature.