Combine the water, teaspoon sugar and yeast in a large mixing bowl and let sit 10 minutes. Add the half cup sugar, flour, butter or margarine, and eggs. Combine by hand or use a dough hook in a stand mixer until all the ingredients are mixed in. Cover bowl with plastic and let rise two to four hours.

Meanwhile, make the filling. Combine sugar and cocoa. Add soft butter or margarine and mix well.

Preheat oven to 375 degrees Fahrenheit. Use spray oil to grease two 12-inch loaf pans.

Divide dough into four. Roll each piece into a 10 X 7 rectangle. Spread one-fourth of filling and roll tightly the long way. When you have two rolls, twist them together, seam side down. Tuck the ends under and place in loaf pan. Do the same for the other two pieces of dough. Brush tops of loaves with reserved egg yolk mixed with a little water.

Bake for 45 minutes. Cool for 20 minutes and then remove from pan. Wrap in foil and freeze unless you will use it by the next day.