In a small saucepan over low heat, heat milk and butter just until butter melts.
Set aside to cool.
In the bowl of an electric mixer, stir together flour, sugar, salt, and yeast.
Add lukewarm butter mixture.
Stir in eggs and egg yolk.
Knead dough until smooth, about 8-10 minutes.
Spray a lidded container with cooking spray.
Place dough in container and cover.
Allow to rise at room temperature for 1 hour.
Place in refrigerator for 12-15 hours.
When ready to bake, turn dough out onto a lightly floured surface.
Cover with a clean cloth or plastic wrap.
Allow to rest for 20-30 minutes.
While dough is resting, spray a 7" loaf pan with cooking spray. Set aside.
Roll dough into a cylinder that is 12"-14" long.
Cut dough in half lengthwise.
Twist dough together.
Place in prepared pan, tucking ends under.
Cover with plastic wrap that has been lightly sprayed with cooking spray.
Leave dough to rise for 1-1 1/2 hours, or until crowning the top of the pan.
While dough is rising, heat oven to 400 degrees F.
Bake for 12-15 minutes until golden brown and cooked through.