Place the shredded Napa cabbage in a bowl, toss with a pinch of salt, and let sit for 10 minutes. Squeeze out all excess moisture with your hands or a clean kitchen towel.

Preheat your oven to 375°F (190°C) and lightly grease a 9x13 inch baking dish.

In a large skillet over medium-high heat, sauté the scallion whites, minced garlic, and ginger until fragrant (about 1 minute).

Add the ground pork to the skillet. Cook, breaking it up with a spoon, until fully browned and caramelized.

Stir in the squeezed cabbage, 2 tablespoons of soy sauce, oyster sauce, white pepper, and toasted sesame oil. Cook for 2 more minutes, then remove from heat.

In a small bowl, whisk together the chicken broth, the remaining 1 tablespoon of soy sauce, and the beaten egg to create the hydration liquid.

Line the bottom of the prepared baking dish with a slightly overlapping layer of wonton wrappers.

Spread one-third of the pork mixture evenly over the wrappers. Drizzle with a few tablespoons of the broth mixture.

Repeat the layers (wrappers, pork, broth) two more times. Finish with a final layer of wonton wrappers on top.

Pour the remaining broth mixture evenly over the top layer of wrappers, ensuring the edges are moistened. Sprinkle evenly with mozzarella cheese.

Cover the dish tightly with aluminum foil and bake for 30 minutes.

Remove the foil and bake for an additional 10-15 minutes until the cheese is golden and the wrapper edges are crispy. Let rest for 15 minutes before garnishing with scallion greens and slicing.