Mix warm milk with quick rise yeast in a bowl and let it sit for about 5 minutes until frothy.

In a stand mixer, add all-purpose flour, sugar, and salt. Once the yeast is frothy, pour it into the mixer and blend on low speed until just combined, then increase to medium speed for 5 minutes until smooth.

Transfer the dough to a greased bowl, cover it, and let it rise in a warm spot for 1 to 18 hours.

Soften cold unsalted butter to room temperature, shape it into an 8x8-inch square, and chill.

Roll the risen dough into a 10x10-inch square. Place the chilled butter disk diagonally in the center, fold the corners over, and seal it in.

Roll out the dough with the butter inside into a rectangle. Fold it into thirds like a letter, refrigerating between folds (repeat 2-3 times).

Roll out the laminated dough into an 8x15-inch rectangle. Brush with melted butter and sprinkle half the cinnamon sugar mix evenly over the top.

Cut the dough into strips, roll them into spirals, and arrange them in a greased muffin tin. Cover and let rise for 20 minutes.

Preheat your oven to 400°F. Bake the buns for 15 minutes, lightly press the tops, and continue baking for an additional 10-15 minutes until golden brown.

Once baked, let them cool slightly. Roll the warm buns in the remaining cinnamon sugar mixture if desired.