Combine the flours, yeast, sugar and salt together in the bowl of a stand mixer. Whisk briefly to combine. Add the whole milk, melted butter and egg yolks. Using the dough hook attachment, begin mixing on medium low until the dough just comes together. Increase the speed to medium and knead until the dough is smooth and pulls away from the sides of the bowl, about 5 minutes. Cover the bowl with plastic wrap and set aside in a warm spot to rise until one and a half times it's size, about 60-90 minutes.
Lightly grease a 9x13 baking dish and set aside. Using a dough scraper or a sharp knife, divide the dough into 15 equal pieces (use a scale if you’d like them to be even in size, dividing the total weight of the dough by 15). Keep the pieces of dough covered with plastic wrap while you work with one piece at a time.
Working with one piece at a time, gather up the edges of the dough into a rough ball shape, pinching the dough where the edges come together to create a “belly button”. Place the ball, belly button side down, on a clean, unfloured work surface. Cupping the ball with your hand so that your palm is lightly resting on the dough and your fingertips are resting on the counter, make small circles with the dough until a tight ball is formed. Place the ball in the prepared baking dish and cover the dish with plastic wrap while you repeat the process with remaining pieces of dough. When you are finished shaping, the dough balls should be evenly spaced in the baking dish, 5 rows of 3.
Cover the baking dish with plastic wrap and let the rolls rise in warm spot until they are nearly touching, about 45 minutes.
Meanwhile, heat the oven to 375 degrees. Bake the rolls until puffed and nicely browned, about 20-25 minutes. Cover the baking dish with a lint-free kitchen towel while the rolls cool for 20 minutes (this helps keep the crust of the rolls soft). Brush the tops with melted butter. Serve warm.