Warm your milk to 110°F and pour it into a mixing bowl. Sprinkle in the instant yeast and granulated sugar, gently stirring to combine. Let this mixture sit for about 5-10 minutes until it becomes frothy.

In a large bowl, whisk together the all-purpose flour, cocoa powder, salt, and red food coloring until evenly combined. Create a well in the center and add the yeast mixture along with the melted butter, egg, and buttermilk. Mix until a soft dough forms, then turn it out onto a floured surface and knead for 7-8 minutes until smooth and elastic.

Place the dough into a greased bowl, turning it to coat all sides with oil. Cover the bowl with plastic wrap or a clean kitchen towel, and set aside in a warm area. Allow the dough to rise for about 1 hour, or until it has doubled in size.

While the dough is rising, prepare the filling by combining brown sugar, granulated sugar, cocoa powder, and ground cinnamon in a small bowl. Mix until fully combined.

Once the dough has risen, punch it down to release air bubbles and turn it out onto a floured surface. Roll the dough into a rectangle about 15x10 inches in size. Spread a generous layer of softened butter across the surface, then evenly sprinkle the prepared filling mixture.

Starting from one of the longer edges, carefully roll the dough tightly into a log. Cut the log into 12 equal pieces. Place the cut rolls on their sides in a greased baking dish.

Cover your baking dish with plastic wrap or a kitchen towel and let the rolls rise in a warm place for another 30-40 minutes.

Preheat your oven to 350°F while the rolls are rising. Bake the rolls for 20-25 minutes until golden brown.

While the rolls are baking, whisk together the powdered sugar, milk, and vanilla extract until smooth. Adjust the milk quantity to achieve your desired glaze consistency.

Allow the rolls to cool for about 5 minutes before drizzling the glaze generously over the warm rolls. Serve immediately.