Step 1: Preheat your oven to 400°F (200°C) if baking, or prepare a non-stick skillet with a light layer of oil over medium heat if pan-frying. Line a baking sheet with parchment paper if baking.
Step 2: On a lightly floured surface, unroll the pizza dough. Gently roll it out slightly to form a large rectangle. Cut the dough into 6-8 equal squares or rectangles.
Step 3: On one half of each dough piece, spread about 1 tablespoon of pizza sauce, leaving a small border around the edges. Top with 2-3 tablespoons of shredded mozzarella cheese and any desired optional fillings.
Step 4: Fold the plain half of the dough over the filling to create a pocket. Press the edges together firmly to seal, then use the tines of a fork to crimp the edges all around, ensuring a tight seal.
Step 5: If baking: Brush the tops of the sealed pockets with the egg wash. Place them on the prepared baking sheet. If pan-frying (no-bake): Carefully place the pockets into the heated, lightly oiled skillet.
Step 6: If baking: Bake for 12-15 minutes, or until the crust is golden brown and the cheese is melted and bubbly. If pan-frying: Cook for 3-4 minutes per side until golden brown and cooked through. Serve warm with extra pizza sauce for dipping, if desired.