Activate Yeast: Warm 1 cup of milk to about 110°F, mix with 2 tablespoons of granulated sugar and 2 teaspoons of instant yeast. Let sit for 5 minutes until frothy.

Make Dough: In a large bowl, combine flour, sugar, cocoa powder, and salt. Add yeast mixture, egg, butter, and buttermilk. Mix until a soft dough forms.

First Rise: Knead dough on floured surface for 5-7 minutes until smooth. Place in a greased bowl, cover, and let rise in a warm spot for 1 hour.

Prepare Filling: Mix brown sugar, granulated sugar, cinnamon, and cocoa powder in a bowl. Set aside.

Roll Out Dough: Punch down dough, roll out into a 12x16-inch rectangle. Spread 1/4 cup softened butter and sprinkle filling mixture.

Roll and Cut: Roll dough into a log and slice into 12 equal pieces.

Second Rise: Place rolls in a greased baking dish, cover, and let rise for 30-40 minutes.

Bake Rolls: Preheat oven to 350°F, bake rolls for 20-25 minutes until golden brown.

Make Glaze: Whisk powdered sugar, milk, and vanilla extract until smooth.

Glaze and Serve: Let rolls cool for 5 minutes, drizzle with glaze, and serve.