Thaw one roll of phyllo dough according to packaging instructions
Preheat oven to 375ºF. Line a 9x13 sheet pan with parchment paper. Spray with cooking spray
In a small mixing bowl, whisk together egg white, 2 tbsp olive oil, and water
Unroll and cover phyllo sheets with plastic wrap and then a slightly damp towel to prevent drying out. Place one sheet of phyllo on baking sheet and lightly brush with egg white mixture
Repeat with remaining sheets of phyllo dough
Brush top layer with 1 tbsp olive oil
Bake for 8 minutes or just until the phyllo starts to brown
Spread tomato sauce evenly over dough. Sprinkle with cheese and top with pepperoni
Bake 10-12 minutes or until cheese starts to melt. Remove from oven, slice, and serve