Using a large bowl, add 2 cups flour, cocoa powder, sugar, yeast and salt; stir until well combined. Set bowl aside.

Using a microwave-safe bowl, add water and butter. Microwave in 15-seconds intervals until very warm but not hot to the touch. (The target temperature is 120°F-130°F. The butter will not melt completely.)

Add water and butter mixture to the bowl with the dry ingredients. Add egg.

Using an electric mixer, beat on medium speed for 2 minutes, or until smooth. (Don’t forget to scrape sides and bottom of bowl occasionally.)

Add 2 more cups of flour; beat on high speed for 2 minutes.

Add just enough of the remaining flour for dough to come together and form a ball when mixed on medium speed. (Note: I used ¾ cup of flour at this stage.)

Transfer dough to a lightly-floured work surface and knead for 6-8 minutes, or until dough is smooth and elastic. (Note: Dough should spring back when lightly pressed with two fingers.)

Cover dough with a towel; let rest for 10 minutes.

Using a medium mixing bowl, add sugar, cinnamon and chocolate chips; stir until well combined. Set bowl aside.

Using a rolling pin, roll dough into a 10”x15” rectangle.

Spread softened butter evenly over dough, leaving ½” border on each of the longer sides. Sprinkle filling mixture evenly on top of butter.

Beginning with a long side of the rectangle, roll dough up tightly. Pinch seams together to seal.

Using a sharp knife, slice dough into 12 equal pieces. (Tip: A piece of unflavored dental floss is a great way to slice cinnamon rolls. Simply slide floss under the rolls, bring both ends up and cross over to cut dough.)

Place pieces cut-side down into a greased 9”x13” baking pan.

Cover pan with towel and let rise in a warm place for 1 hour, or until doubled in size.

Preheat oven to 350°F.

Bake for 25-30 minutes, or until tops of rolls are golden brown. Let pan cool on a wire rack for 20 minutes.

Using a medium saucepan, add butter and place over medium heat.

Once butter has melted, add marshmallows, milk and vanilla extract. Continue to cook, stirring often, for 3-4 minutes, or until marshmallows have melted and mixture is smooth.

Remove from heat and add powdered sugar; stir until well combined. (If necessary, add a bit more milk to make glaze easier to drizzle onto cinnamon rolls.)

Using a piping bag with a small round tip (or a sandwich bag with one corner snipped off), drizzle glaze on top of cooled rolls.