Heat oven to 350°F. Spray 9-inch glass pie plate with cooking spray. In 10-inch skillet, cook beef and onion over medium-high heat, stirring frequently, until beef is thoroughly cooked; drain. Stir in pizza sauce until well mixed.
Carefully unroll dough in pie pan so edges extend over sides. Pat dough in bottom and up sides of pan, leaving dough extended over sides. Spoon beef mixture into crust. Top with half of the cheese, the pepperoni and remaining cheese.
In small bowl, slightly beat egg and water. Fold extended edges of dough up and over filling; seal all edges. Brush crust with egg mixture.
Bake 38 to 48 minutes or until deep golden brown. Cool 15 minutes. Cut pizza into wedges; serve with additional pizza sauce.