COMBINE yeast with warm water in the bowl of a stand mixer fitted with the dough hook. Let stand until frothy, 10 min. Beat in warm milk, ¼ cup melted butter and yolks until combined. Add flour, granulated sugar and salt (2). Beat on medium, until dough is smooth and pulls cleanly away from the bottom and sides of bowl, 4 to 6 min. Transfer to a lightly oiled bowl and cover loosely with a damp kitchen towel. Let rest until dough is doubled in size, about 1 hour.

PREHEAT oven to 325F. Line a baking sheet with parchment. Stir ½ cup butter with brown sugar and cinnamon in a small bowl. Beat egg with 1 tbsp water in a small bowl until combined.

ROLL dough on a lightly floured surface into a 22 × 12 in. rectangle, trimming edges if needed. Spread butter mixture evenly over dough to the edges. With the long edge facing you, tightly roll up dough in jelly roll fashion (3). End roll with seam-side up. Use a sharp knife to cut the log lengthwise in half along the seam (4). Tightly weave the two pieces together, leaving the cut sides exposed. Gently transfer to prepared sheet. Brush a 2-in. portion of one woven end with egg wash (5). Form into a wreath, firmly pinching the egg-washed end underneath the other to seal (6). Cover with same damp kitchen towel and let rise until doubled, 1 more hour.

BAKE in centre of oven until bread is deep golden, 35 to 40 min. Cool slightly. Dust with icing sugar before serving.