In a large bowl, sprinkle the yeast over the warm water, add the remaining 1 teaspoon sugar, stir, and set aside in a warm place for 10 minutes to proof, until the mixture is foamy. Add the lukewarm milk mixture and the eggs and beat until well combined. Add the dough enhancer and then the flour 1 cup at a time, stirring and using enough flour to form a stiff dough. Turn out on a floured board and knead until smooth and satiny, about 10 minutes. (Or place in the bowl of a stand mixer and knead with a dough hook until the dough cleans the sides of the bowl, about 5 minutes.) Place the dough in a very large buttered bowl, turn to butter the top, and allow to rise, covered loosely with a kitchen towel, in a warm place until doubled in bulk, about 1 hour.