Prepare Yeast: Combine 1/2 cup warmed milk and 2 tsp active dry yeast, let sit for 5-10 minutes until frothy.

Mix Dough: In a mixing bowl, whisk 3 cups flour, 1/4 cup cocoa, 1/4 cup brown sugar, 1 tsp salt. Add yeast mixture, 1 egg, and 1/4 cup butter. Mix until smooth.

First Rise: Transfer to greased bowl, cover, and let rise for 1½ to 2 hours until doubled in size.

Prepare Filling: Mix 1/2 cup brown sugar, 1/4 cup cocoa, 1 tbsp cinnamon, and 1 tsp vanilla in a bowl.

Roll Out Dough: Dust surface with flour, roll dough into 12x18 inches. Spread 1/4 cup butter on surface, and sprinkle filling mixture over it.

Shape Rolls: Roll dough tightly from long edge, slice into 9-11 pieces.

Second Rise: Place in a greased baking dish, cover, and let rise for 30-60 minutes until puffy.

Bake: Preheat oven to 350°F (180°C). Bake rolls for about 20 minutes until lightly golden.

Glaze: Mix 1 cup powdered sugar, 2 tbsp cocoa, and 2-3 tbsp cream until smooth.

Serve: Drizzle glaze over warm rolls and allow to cool slightly before serving.