Combine warm milk, yeast, and sugar. Let foam 5 minutes, then mix in discard, butter, and egg. Add flour and salt. Knead 8 minutes into a smooth, soft dough.

Place dough in a greased bowl, cover, and rise until doubled, 1 to 1 1/2 hours.

Stir together the 3 tbsp soft butter, brown sugar, and cinnamon into a spreadable paste.

Divide dough into 4 equal pieces. Roll each into a 10-inch circle. Layer on parchment with filling between each, leaving the top plain.

Set a 2 1/2-inch cutter in the center as a guide. Cut 16 strips from the edge to the center. Twist pairs of strips away from each other 5 times and pinch ends to seal.

Rest 30 minutes, preheat oven to 350°F. Brush with egg wash, sprinkle coarse sugar. Bake 25 to 30 minutes until golden. Cool 5 minutes and serve warm.