Combine the flour, yeast, sugar and salt in a large bowl. Heat milk, water and butter until warm (120°). Add to the flour mixture and mix well. Knead on lightly floured surface until smooth and elastic, about 8 to 10 minutes. Cover and let rest for 30 minutes.
Divide dough into 8 equal pieces and shape into balls. Work with one piece at a time, keeping the remaining pieces covered under plastic wrap that has been coated with non-stick cooking spray.
Roll the piece of dough with a rolling pin until it's thin.
Starting with a short side, roll the dough up tightly and pinch the seams and ends to seal. You can stuff the bread with mozzarella cheese or guava paste, placing a piece at the top of the dough and rolling it in to cover.
Place on a prepared baking sheet and repeat with remaining pieces of dough. Cover and let rise in warm place until doubled in size, about 60 minutes.Brush with the beaten egg.
Bake in preheated 375°F oven for about 20 minutes or until done.Remove from pan and brush with additional melted butter, if desired. Serve warm.