Place the milk, butter, sugar, eggs, egg yolk, flour, salt, and yeast in the bowl of a stand mixer fitted with the dough hook and start kneading on medium low speed.
Let the machine do the work, turning the sticky mess into a soft, glossy dough ball. This may take 20 minutes or more to achieve.
Transfer the dough ball to an oiled mixing bowl, cover, and let it rest in the refrigerator overnight, or at least 8 hours.
Take the dough out of the refrigerator and divide it in half with a sharp knife.
Separate each half into 3 equal portions.
Roll out those portions into long ropes, about 12 inches long.
Braid 3 of the ropes together, pinching the ends together. Repeat with the remaining 3 ropes.
Take out 2 loaf pans; if using nonstick, you can put the dough right in the pan. If you're using stoneware, make sure to grease with butter first. Place the braided loaves into the pans and cover.
Put in a warm place to rise, about 3 hours. It won't exactly double in size, but it should get nice and puffy.
When you're getting close to time to bake, preheat oven to 350 degrees Fahrenheit.
Brush the proofed bread loaves with the egg white and sprinkle 1 Tablespoon of pearl sugar over the top of each.
Bake on the middle rack for 40-45 minutes, tenting the tops with foil after 20 minutes.
Remove to a wire rack to cool.