In the bowl of a stand mixer fitted with a dough hook, combine the water, honey, and yeast. Stir and let sit for 5 to 10 minutes to proof until the yeast is foamy.
Once the yeast is looking bubbly, add the molasses, cocoa powder, oil, honey, salt, and 2 cups of the whole wheat flour. Mix until combined.
With the mixer running, gradually add the rest of the flour starting with the whole wheat, then adding the bread flour until the dough pulls away from the sides of the bowl (you may not need the last cup of flour). Knead for 5-7 minutes. The dough should be soft and slightly tacky.
Transfer the dough to a large, lightly greased bowl, then cover with a sheet of plastic wrap lightly sprayed with cooking spray, or cover with a light dish towel. Let rise until doubled in size, usually about 60 to 90 minutes depending on how warm it is inside your house.
Punch down the dough and use a bench scraper, pizza cutter, or sharp knife to divide it into 16 evenly sized balls. Pinch the bottom of each roll together for form a nice round roll shape, then place in a lightly greased 9x13-inch baking pan. Repeat with each ball of dough.
Lightly cover with plastic wrap or a dish towel and let rise again until puffy and doubled in size (another 45-60 minutes). Just before baking gently brush the rolls with the melted butter and sprinkle with the oats, if desired.
Preheat the oven to 375 degrees F. Bake for 18-20 minutes.