Place the half and half and water in a small microwavable bowl and heat for about 20 seconds, until the temperature reaches 110°F- 115°F (43°C- 46°C) on a thermometer. Remove from the microwave and stir in the yeast.

Place 3 cups of the flour in the bowl of an electric mixer. Add the sugar, cocoa, salt, eggs, butter, sour cream and vanilla. Using the mixing paddle, turn on the mixer to combine the ingredients. Pour in the yeast mixture and allow the mixer combine for about 2 minutes. Stop the mixer and remove the mixing paddle. Scrape down the dough in the bowl from the sides and stir once or twice.

Place the kneading hook on the mixer and begin to knead the dough while adding small amounts of the remaining flour. Continue to knead all of the dough for about 5 minutes in the mixer until the flour is absorbed. The dough will still be somewhat soft and sticky. Remove the dough from the mixer and knead by hand on a well-floured surface until the dough is cohesive, no longer sticky, but softer than a regular bread dough. Place in a clean bowl that has been greased, cover with a towel, and allow to rise for one hour until doubled in bulk.

Punch down the dough, and then roll out the dough on a large piece of parchment paper into a large rectangle about ½” (1cm) thick. Mix together the filling sugar and cinnamon, and sprinkle evenly over the surface of the dough rectangle along with the chopped pecans. Starting with the long edge, roll the rectangle into a long roll, and join the ends together to form a ring. Using scissors, make 16 cuts into the ring without severing into separate pieces. Twist each section so that the pinwheel pattern of the interior of the roll faces up. Leaving hte dough ring on the parchment paper, slide the dough ring onto a cookie sheet. Cover lightly with a towel, and allow to rise again for 1 hour.

Heat your oven to 350°F (176°C). Once the ring has completely risen, brush each portion with butter. Place the bread  in the oven, and bake for 40-45 minutes, until the bread is firm. Once baked, remove from the oven and allow to cool slightly while you prepare the glaze.

For the glaze, heat the chocolate and butter in a double boiler until they are gently melted. Using a whisk, add the powdered sugar and vanilla, whisking until well combined. Remove the double boiler from the heat and drizzle the glaze over the ring while both the glaze and the ring are still warm. Allow to cool before slicing and serving.