In a mixer bowl, add the yeast, sprinkle with a pinch of sugar, and pour the warmed milk in. Allow the yeast to activate and foam up, about 5-10 minutes.
Add the flour and salt to a small bowl, fluffing to combine with a fork.
In the meantime, in another small bowl, combine the 1/4 cup and 2 tablespoons of sugar with the egg and egg yolk. Whisk to combine and when the yeast is ready, add this to the mixer bowl and whisk by hand with the yeast.
Add the flour/salt mixture to the mixer, stir a few times by hand with a spatula or whisk, attach the bread hook to the mixer, start it on low then add the butter. Knead the ingredients on low for about 10 minutes, until the dough is soft and smooth.
Remove the dough from the mixer bowl and knead briefly by hand on a lightly floured surface to bring the dough to a smooth rounded ball.
Spray a large bowl with cooking spray and place the dough in the bowl, turning to coat the surface with the oil. Cover with plastic wrap and let rise to double in size in a warm spot for about 1 to 1 1/2 hours.
Filling:
In a small bowl, add the filling ingredients, the chocolate, sugar, and cinnamon, then cut in the butter, rubbing it in with your fingers. It will be quite chunky. Scoop out 1/2 cup and set both aside.
Topping:
In a small bowl, add the crumb ingredients, the powdered sugar, flour, and butter. Combine in the same fashion as the filling, cutting in the butter with your fingers. Add the reserved 1/2 cup of filling to the topping and set aside in the refrigerator.
Assembly:
Punch down the risen dough, flour a work surface, and transfer the dough to it. Let the dough sit for 5 minutes to rest. Mix up the assembly egg wash, the egg and cream, whisking well with a fork.
Roll the dough into an 18” square and brush the edges with the egg wash. Spread the filling ingredients evenly over the dough. Be sure to leave a 1 inch border around the edges.
Roll the dough into a log, pinching the seams together. Form the dough into a U shape then twist the U ends together to form a twisted type braid.
Lightly grease a loaf pan and line with parchment paper, ensuring the edges of the paper hang over. Lightly grease or butter the paper and place the dough in the pan. Brush the remainder of the egg wash onto the top then sprinkle the crumb topping with the 1/2 cup of reserved filling. Cover with plastic wrap and let rise for 20-30 minutes, until the dough rises about half.
Begin preheating the oven to 350° F (175° C) then bake for about 55 minutes, until the top is golden. Rotate the pan halfway through baking. Lower the oven temperature to 325° F (163° C) and bake for an additional 15-20 minutes to reach a deep golden color.