Butter a 9x13 inch pan.

In a large mixing bowl whisk together 2 cups flour, cocoa powder, sugar, yeast, and salt.

Combine water and butter in a bowl or liquid measuring cup and microwave for 20 seconds at a time until butter is mostly melted. (The water should be very warm but not too hot to touch).

Add water mixture and egg to the dry ingredients and mix well.

Add flour ¼ cup at a time, until dough just starts to come together in a ball. (It will still be quite sticky, but you should be able to handle the dough with floured hands.)

With floured hands, transfer dough to a lightly floured surface and knead for 4-6 minutes until smooth and elastic.

Place dough in a bowl, cover tightly with plastic wrap, and let rise in a warm place for 10 minutes.

Roll dough into a large flat rectangle (about 15x10 inches).

Spread softened butter all over the dough. Stir together cinnamon and sugar and sprinkle all over the buttered dough.

Beginning with the long side of the rectangle, roll tightly to the opposite side and pinch the seam to seal.

Use a sharp knife (or use the dental floss trick!) to cut dough into 12 equal-sized sections.

Arrange cinnamon rolls cut-side-down in the buttered baking pan.

Cover tightly and allow to rise in a warm place for 1 hour or until doubled in size. Meanwhile, preheat oven to 350 degrees.

Bake in preheated oven for 25-35 minutes until no longer doughy. Cool on wire rack at least 20 minutes.

Prepare the icing by whipping the butter (with a whisk or electric hand mixture) for 2-3 minutes until light and fluffy. Mix in 2 cups powdered sugar.

Add hazelnut spread and salt and cream together until completely incorporated. Add remaining powdered sugar and milk, one tablespoon at a time, until icing is smooth and easily spreadable.

Spread icing over cinnamon rolls and serve.