Korvapuustit (Finnish Cinnamon Rolls)

To make the dough:

1. In a small bowl, sprinkle the yeast over the lukewarm milk. Stir briefly to combine, then allow to sit at room temperature until frothy, about 10 minutes.
2. In the bowl of a stand mixer fitted with a dough hook or a large bowl, combine the flour, sugar, cardamom, and salt.
3. Mix in the softened butter, egg, and frothy yeast with milk to bring together the dough.
4. On a lightly floured surface, knead the dough until soft and smooth. After mixing, if the dough is still too crumbly and just won't come together, add a splash more lukewarm milk at a time. If just too sticky to handle, slowly add just a little more flour.
5. Place the dough back in the bowl, cover with plastic wrap or a towel, and allow to rise at room temperature until doubled, about 2 hours.

To assemble:

1. Preheat oven to 400˚F (200˚C). Line two rimmed baking sheets with parchment or lightly grease.
2. In a small bowl, whisk together the sugar and cinnamon.
3. On a lightly floured surface, roll the dough into a large, thin rectangle about 12 x 24 inches (30.5 x 61 centimeters).
4. Gently cover the top of the rectangle with the softened butter, taking care not to tear the dough. Keep a 1/2 inch (1.25 centimeter) clear border around the edges.
5. Cover the butter evenly with the cinnamon sugar mixture.
6. Tightly roll up the rectangle, long side to long side, pinching the seam to seal.
7. Use a sharp knife to make diagonal cuts across the roll at an angle about 2 inches (5 centimeters) apart, alternating the direction of the cut, to make individual rolls with a short side and a long side in a triangle shape.
8. Place the rolls long side down on the prepared baking sheets at least 2 inches (5 centimeters) apart.
9. Use your finger to press down in the center of each roll to fan out the spiraled edges.
10. Cover the baking sheets with towels and allow to rest at room temperature until puffed, about 30 minutes.
11. In a small bowl, beat the egg, then brush gently over the puffed rolls. Top the center of each roll with a sprinkling of the pearl sugar.
12. Bake in the preheated oven until golden, about 10-14 minutes.
13. The Korvapuustit are best warm from the oven and the day they are baked.