In a stand mixer bowl, combine warm milk, sugar, instant yeast, eggs, bread flour, and salt. Knead for 4-5 minutes until a cohesive dough forms.
With the mixer running, gradually add 115g softened butter a little at a time, kneading for another 5-7 minutes until smooth and elastic.
Divide dough into two equal halves. Place plain half in a greased bowl and cover.
Return second half to mixer; add 15g cocoa powder, 1 tbsp warm milk, and 1 tbsp extra softened butter. Knead 3-4 minutes until uniform chocolate dough forms. Place in a separate greased bowl.
Cover both bowls and let rise in a warm spot for 1 to 1.5 hours until doubled in size.
Roll each dough half into a long 45-50 cm (18-20 inch) log. Twist logs tightly around each other, coil into a circle, and roll flat into a 30x45 cm (12x18 inch) rectangle.
Mix filling ingredients (115g butter, brown sugar, cinnamon, salt) and spread evenly over rolled marbled dough.
Roll dough tightly into a log and cut into 12 rolls using dental floss. Place in a greased 9x13 inch baking dish, cover, and let rise for 35-45 minutes.
Bake at 175°C (350°F) for 22-27 minutes until golden brown.
Whisk cream cheese, 60g butter, and powdered sugar until smooth. Spread over warm rolls before serving.