In a mug, microwave milk for about 20 seconds until it is lukewarm, NOT HOT (about 105-115°F.). Stir in yeast and allow to sit for 10-15 minutes until the top of the mixture looks foamy.*
In a medium bowl, whisk together milk and yeast mixture, melted butter, sugar, egg yolk, and salt.
Add the flour, a third at a time, and use a spoon to mix well, until a thick, sticky dough forms and all the flour is incorporated.
Dump the mixture onto a well-floured work surface and knead just until the dough is no longer sticky and forms a ball (about 10 folds).
Place dough into a greased bowl, cover with a towel, and allow to rise in a warm place for an hour, or until doubled in size.
Lightly grease a 6 to 7-inch baking dish.
Stir together brown sugar and cinnamon.
Once your dough has risen, turn out on a lightly floured surface and squish and stretch it GENTLY (we don't want to rip it) into an oblong shape and then use a lightly floured rolling pin to roll the dough out to about 5 by 15 inches. Gently manipulate the corners and sides so you have a nice rectangle.
Spread butter over the entire thing and top with the brown sugar mixture. Sprinkle with chocolate chips. Roll from the short side and use a serrated knife to cut the roll into quarters. Place in prepared baking dish. (If making over night, skip to notes.)
Allow the rolls to complete their second rise in a warm place for 30 minutes.
Preheat oven to 400°F. Cook rolls 12-15 minutes until the tops are golden and centers cooked through (cover with foil during the last few minutes of cooking time if browning too quickly).
While your rolls bake, In a medium bowl, whisk together sifted powdered sugar, espresso, vanilla, and salt.
Spoon glaze over warm rolls, serve, and enjoy.
Overnight Rolls: Cover rolls tightly in plastic wrap, and place in the fridge overnight or up to 24 hours.Remove plastic wrap from rolls and place them into a cold oven. Turn your oven to 400 degrees and bake for 15-20 minutes until the tops are golden and center cooked through. Watch closely--they go from pale to over-done very quickly. If they begin to brown too quickly, before the centers are done, cover with foil until finished baking.*If your yeast and milk mixture does not foam, your yeast may be bad, or may have been killed if the milk was too hot. Toss and try again, making sure the milk is just lukewarm.*For best results, measure flour by weight or the Spoon and Sweep Method (spoon flour into your measuring cup, swipe excess off with the flat of a knife).