3 tablespoons heavy cream or enough to make a pourable glaze
In a small saucepan combine milk, butter, and sugar. Stir until the sugar has dissolved and the butter has melted completely. Remove from heat and allow mixture to cool from hot to just warm.
Place sweet milk and butter mixture in a large mixing bowl and sprinkle yeast over the liquid. Stir to incorporate. Allow mixture to sit for 5 minutes to allow to yeast to activate, foam, and froth.
Add 1 1/2 cups flour, salt, and the egg yolk to the milk and yeast mixture. Use a wooden spoon or hand beaters with the dough hook attachment and stir or beat until incorporated. Add more flour, a few tablespoons at a time if the dough feels to wet. Bring the dough together into a ball and knead a few turns with your hands.
Cover the bowl with plastic wrap and allow to rest for 10 minutes.
Roll the dough out on a lightly floured work surface. Roll into a roughly 9 x 12-inch rectangle.
Spread with about 4 tablespoons of butter. In a small bowl stir together sugar, cinnamon, espresso powder, cocoa powder, and salt. Generously sprinkle over the melted butter. Sprinkle with chocolate chips. Roll starting at the longer edge into a tight coil.
Slice into 6 pieces.
Use remaining 2 tablespoons of butter to lightly grease the bottom and sides of an 8×8-inch baking pan. Place rolls in the pan leaving about 1/2 inch of room between them. Cover with plastic wrap and allow to rise for 30 minutes.
While the rolls rise, place a rack in the upper third of the oven and preheat oven to 350 degrees F.
Remove plastic wrap and bake the rolls for 18-20 minutes or until golden brown, puffed, and bubbling.
Remove from the oven, allow to cool just slightly.
In a small bowl whisk together powdered sugar, espresso powder, and heavy cream. Drizzle over warm rolls and enjoy!!