In the bowl of an electric mixer, add 2 cups of flour, plus the sugar, salt and yeast. Mix once or twice to combine.
In a glass measuring cup, combine the milk, water and butter. Microwave the milk mixture for 45-60 seconds on high, until the butter melts. Remove from microwave, and make sure the temperature measures between 105°-115°F. Heat or cool as needed to reach this temperature range. Add the heated milk mixture to the flour in the mixer bowl, and mix until combined, about 1 minute. Add the orange flower water, eggs and egg yolk, and mix for another minute.
Remove the mixing beater from the mixer, scrape off any remaining dough and return to the bowl, and affix the kneading hook. Begin kneading, adding ½ cup at a time of the remaining flour until you have a cohesive dough, with the dough pulling away from the sides of the bowl. Knead the dough for 5-7 minutes on medium speed.
Once the dough is no longer sticky, and the bowl has fewer pieces of dough stuck to the sides, this is a sign that the dough is completely kneaded. Turn off the mixer, and scrape any excess dough from the dough hook. Place the dough in a greased bowl, turning over once in the bowl to grease the outer surface of the bread. Cover, and allow to rise for 1 hour in a warm (70°-80°F) draft free environment.
After the dough has risen, punch it down and allow to rest for 10 minutes.
Separate a portion of the dough to make the shaped topping; the portion should be slightly smaller than a tennis ball. Divide this small portion into 4 smaller portions. Shape the large remaining portion of dough into a round loaf, and place on a greased baking sheet. Take one of the four smaller portions, and roll on the countertop into a cylinder. Press an indentation into the middle of the cylinder as you roll it, and then press two more indentations on either side of the middle. Lay the long indented cylinder across the top of the round loaf. Shape two more of the smaller portions in the same fashion, laying them across the top of the round loaf to form a star shape with six arms. Take the remaining smaller portion, roll it into a ball, and press in the center meeting point of the six armed star. Place the decorated loaf in a draft free area, and allow to rise for another hour, until it has doubled in bulk.
Meanwhile, heat your oven to 350°F for at least 15 minutes before your decorated loaf is completely risen.
Place the decorated round loaf in the heated oven, and bake for 25-30 minutes, until it is brown.
Remove the loaf from the oven, and immediately brush the entire surface generously with melted butter. Sprinkle over the granulated sugar, and allow to cool completely. Shake off the excess sugar before serving.
Note: Orange flower water, also known as Agua de Azahar is a distillation of water and orange blossoms, and can be found in Middle Eastern and gourmet grocery stores, especially during the holiday season.