Preheat your oven to 375°F (190°C). Prepare a glass baking dish large enough to hold all six wrap pockets.

Place a large skillet over medium heat. Add the ground beef and diced onion. Cook for 7 to 10 minutes, stirring frequently and breaking the beef into small pieces, until the meat is fully browned and the onion is softened. Drain any excess grease if necessary.

Add the taco seasoning and tomato sauce to the cooked beef mixture. Stir thoroughly until the beef is evenly coated. Reduce the heat slightly and simmer for 5 minutes, stirring occasionally, until the sauce thickens and the filling becomes rich and flavorful. Remove from the heat and allow to cool slightly.

Place each flour tortilla on a clean cutting board. Using a sharp knife or pizza cutter, trim the top and bottom by cutting straight across the rounded edges. This will create a wide rectangular shape that is easier to fold into a pocket.

Stack the trimmed tortillas and wrap them in a slightly damp kitchen towel. Microwave for 30 to 40 seconds until warm, soft, and flexible. This helps prevent the tortillas from cracking during folding.

Lay one softened tortilla flat on your work surface. Spoon approximately one-sixth of the seasoned beef mixture into the center, spreading it into an even rectangular layer. Leave enough space around the edges to fold and seal the pocket.

Sprinkle approximately 1/4 cup of shredded mozzarella cheese evenly over the beef filling. Repeat with the remaining tortillas, beef mixture, and mozzarella cheese.

Take one long side of each tortilla and fold it inward over the beef and cheese filling, keeping the filling neatly tucked inside.

Lightly brush the exposed tortilla edge with beaten egg. Fold the opposite long side over the first fold and gently press along the overlapping edges to seal. The finished wrap should resemble a flat rectangular pocket. Make sure the filling is securely enclosed.

Arrange the filled pockets seam-side up in the prepared glass baking dish, placing them closely side by side so they support one another during baking. Alternatively, position them seam-side down for a more secure seal.

Sprinkle the shredded cheddar cheese evenly over the tops of all six pockets, making sure each receives a generous coating.

Transfer the baking dish to the preheated oven. Bake for 15 to 20 minutes, or until the tortillas are lightly golden, the edges are slightly crisp, and the cheddar cheese is completely melted and bubbly.

Remove the baking dish from the oven and allow the pockets to rest for 3 to 5 minutes. This helps the filling settle and makes the pockets easier to serve.

Sprinkle freshly chopped parsley over the baked pockets for added color and freshness. Serve warm while the cheese is still melted and the beef filling is juicy.