In a small bowl, mix together both sugars and cinnamon. Set aside.
Warm the milk to 110 degrees. You can do this by placing the milk in a microwave oven for 30 seconds on high power. Whisk warmed milk with melted butter and egg yolks until thoroughly combined.
In the bowl of a standing mixer fitted with a dough hook, mix together 31/2 cups flour, yeast, salt and 1/4 cup cinnamon-sugar mixture.
With the mixer on low, slowly add the milk until the dough comes together. Increase the speed to medium-low and continue mixing until the dough is smooth and elastic, about 8 minutes. If, after 4 minutes, the dough remains sticky, add the remaining flour, 2 tablespoons at a time, until the dough pulls away from the sides of the bowl but sticks to the bottom.
Turn out the dough onto a lightly floured surface and shape into a smooth, round ball. Place the dough into a large, oiled bowl, then flip it so the oiled surface is on top. Cover with plastic wrap and let rise in a warm place until doubled in size, about an hour.
Grease a 9- by 5-inch loaf pan.