Place warm water in a small bowl; stir in yeast and sugar, and let stand until foamy.
In a large bowl, whisk together milk, butter, salt, and 2 eggs. Whisk in yeast mixture when it's foamy.
Using a wooden spoon, stir in 6 cups flour, 1 cup at a time, until you have a soft, shaggy dough. The dough will be sticky, but resist the urge to add more flour: too much flour will result in overly dense rolls.
Transfer dough to a floured work surface; knead until smooth and elastic (at least 5 minutes). The dough will stick to your fingers, which is a sign that it's exactly the consistency you want.
Using a butter spray, line the inside of a large bowl; the bowl needs to be large enough to allow the dough to expand to double its size. Place dough in bowl, turning to coat in butter spray. Cover bowl with plastic wrap or a kitchen towel. Let stand in a warm spot until dough has doubled in size, at least 1 hour.
If you want a more rich flavor - and you have the time - seal the bowl securely with plastic wrap and place in the refrigerator overnight. This will deepen the flavor of the rolls.
Use non-stick canola oil spray to line the compartments of muffin pans. Divide dough into quarters. Roll each into a tube that's about 1 inch in diameter. Cut into 1 inch pieces and roll each into the shape of a ball. Arrange dough balls in the compartments of the muffin pans.
Cover pans loosely with plastic wrap; let stand in a warm spot until rolls have doubled in size. This will take at least 1 hour.
Preheat oven to 375 degrees. In a small bowl, beat remaining egg until blended; brush onto rolls. Sprinkle sesame seeds onto rolls if desired.
Bake for 10 minutes, then rotate pans 180 degrees. Bake for another 10 minutes until golden brown.
