Ingredients:
Kanelstang Dough
70 grams(5 tablespoons) unsalted butter, divided
235 gramsall-purpose flour, divided, plus more for dusting
87 gramswhole milk
50 gramsegg (about 1 large—no need to scoop out extra here)
15 gramssuperfine or granulated sugar
6 grams(about 1¼ teaspoons) fine sea salt, divided
68 gramsripe sourdough starter, 100% hydration
100 gramslight brown sugar
6 gramsground cinnamon
Egg Wash, Topping & Icing
50 gramsegg (about 1 large—no need to scoop out extra here)
29 grams(about 2 tablespoons) whole milk, divided, plus more as needed
50 gramssliced almonds (optional)
50 gramsconfectioners’ sugar
Directions:
Mix the dough (9:00 a.m.)
Cut 56 grams (4 tablespoons) of the butter into small pieces, place it on a plate, and set it aside to soften to room temperature. To the bowl of a stand mixer fitted with the dough hook attachment, add 218 grams of the flour, 87 grams milk, egg, 15 grams sugar, 5 grams of the salt (about 1 teaspoon), and 68 grams ripe sourdough starter. Set the mixer to low speed and mix until all the ingredients are combined and no dry bits of flour remain. Turn the mixer up to medium-low and mix for 3 to 5 minutes until the dough starts to clump around the dough hook. This is a small amount of dough in the mixer, so if at any time the dough fails to effectively move around with the dough hook, you can switch to the paddle attachment. This is a moderately strong dough at this point, but it won’t completely pull away from the bottom of the mixing bowl.
Let the dough rest 10 minutes in the mixing bowl, uncovered.
The butter should be at room temperature by this time (meaning a finger should easily push into a piece with little resistance). With the mixer turned on to low speed, add the butter, one piece at a time, waiting to add the next until the previous is incorporated, 4 to 6 minutes total. Once all of the butter is added, turn the mixer up to medium-low and continue to mix until the dough smooths and once again begins clinging to the dough hook, 2 to 3 minutes. The dough will be cohesive, smooth, and elastic at the end of mixing.
Transfer the dough to another large container (or leave in the mixing bowl) for bulk fermentation.
Bulk ferment the dough (9:30 a.m. to 1:30 p.m.)
Cover the dough with a reusable airtight cover and let it rise at warm room temperature (76°F/24°C) for a total of 4 hours. During this time, you’ll give the dough one set of “stretches and folds” (see next step for explanation) to give it additional strength. This set is performed 1 hour after the start of bulk fermentation. Set a timer for 1 hour and let the dough rest, covered. After 1 hour, give the dough its only set of stretches and folds.
To stretch and fold: An hour after the start of bulk fermentation, wet your hands, grab the north side (the side farthest from you) of the dough, and stretch it up and over to the south side. Then, fold the south side up to the north. Then, perform two more folds, one from east to west and one from west to east. Finally, let the dough rest, covered, for the remaining 3 hours of bulk fermentation.
Chill the dough (1:30 p.m. to 2:30 p.m.)
Check the dough; after 4 hours, it should have risen about 30% in the bulk fermentation container, have a few scattered bubbles, have a smoother and slightly domed surface, and be moderately light and fluffy to the touch. If the dough still looks sluggish or feels dense after 4 hours, give it another 30 minutes to rise in a warm spot. Place the covered bulk fermentation container into the refrigerator for 1 hour. Alternatively, the dough can be left in the refrigerator overnight and the remainder of the steps continued in the morning.
Roll and fill the dough (2:30 p.m.)
Melt the remaining 14 grams of butter, then let cool. Line a half sheet pan with parchment paper and place it near your work surface. In a small mixing bowl, combine the butter, 100 grams brown sugar, remaining 17 grams all-purpose flour, 6 grams cinnamon, and remaining 1 gram (about 1/4 teaspoon) fine sea salt until combined.
Remove the chilled dough from the refrigerator and uncover. It should be cool and semi-firm to the touch. Flour a work surface and use a bowl scraper to scrape the dough out to the floured surface gently. Next, flour the top of the dough and, using a rolling pin, roll the dough out to a rectangle shape that’s about 11 by 16 inches, with the short end closest to your body.
Sprinkle the filling evenly over the dough, pressing down gently to adhere, and leaving a 1-inch gap at the end of the dough farthest from you. Then, as tightly as possible, roll up the dough starting with the (short) end closest to you. When you reach the end, press the dough log down against the bare 1 inch of dough to seal. Transfer the dough to the center of the prepared half sheet pan and cover with a large plastic bag, or use plastic wrap to cover (taking care so the wrap doesn’t fall on the dough).
Proof the rolled dough (3:00 p.m. to 6:30 p.m.)
Proof the dough at a warm temperature (74°F to 76°F/23°C to 24°C is ideal) for about 3 hours 30 minutes to 4 hours. If your kitchen is on the cool side, expect the dough to take longer to proof. Extend the proof time as necessary until the dough has puffed to about double in size and slowly springs back when poked. During the proof time, you might notice the filling slightly leak out of the dough; this is okay (and you can sop it up with a paper towel before baking if desired).
Bake and finish the kanelstang (6:30 p.m.)
Heat the oven to 350°F (175°C) with a rack in the middle. In a small bowl, whisk the egg and 14 grams milk for the egg wash.
Using kitchen shears (or clean scissors), starting at one end of the dough log and working toward the other, cut the dough—almost, but not all the way through the log—into approximately 2-inch pieces at a diagonal. Once the cylinder is cut, alternate pushing each segment outward away from the center (and the one before it). When finished, you’ll have a series of oval-shaped dough petals spread outward in an alternating pattern, resembling a stalk of wheat (see photo).
Lightly brush the entire surface of the dough with the egg wash, sprinkle on the sliced almonds (if using), and bake for 15 minutes. After 15 minutes, rotate the pan back to front and bake for another 10 to 15 minutes, until the kanelstang is puffed and mostly golden with spots of light brown. Remove from the oven and let cool on the sheet pan placed on top of a wire rack for 15 minutes.
For the icing, in a small bowl, whisk together the confectioners’ sugar and remaining 15 grams milk (using a little more milk as necessary to thin the icing so it slowly runs off the end of a spoon). Then, drizzle the icing over the cooled kanelstang before serving. This is best the day it’s baked, but can be stored in the fridge for up to 5 days; reheat gently in a 350°F (175°C) oven for 5 minutes.