Preheat the oven to 425°F (220°C) and line a baking sheet with parchment paper.
On a lightly floured surface, roll out the refrigerated pizza dough to form a large rectangle, approximately 1/4 inch thick. Cut the dough into squares, each about 4x4 inches.
In a medium-sized bowl, combine the marinara sauce, shredded mozzarella cheese, diced pepperoni, sliced bell peppers, finely chopped onions, dried oregano, garlic powder, and a pinch of salt and pepper. Mix thoroughly until well incorporated.
Take a square of dough and place a generous spoonful of the filling mixture in the center. Avoid overfilling.
Fold the dough square over the filling to create a triangle shape. Press the edges firmly to seal, then use a fork to crimp the edges.
In a small bowl, beat the egg until well blended. Brush the egg wash over the top of each pocket.
Transfer the sealed pizza pockets to the prepared baking sheet and bake for 12 to 15 minutes, or until puffed and golden brown.
Allow the pizza pockets to cool for a few minutes before serving warm with extra marinara sauce on the side.
Notes
For an inviting presentation, serve the pizza pockets on a rustic wooden board or a vibrant plate. Garnish with fresh basil leaves or a light sprinkle of Italian seasoning to add color and aroma.