Preheat the oven to 400°F (200°C).
Prepare the dough by mixing all-purpose flour with cold butter and cold water until a smooth dough forms. Chill the dough for 15 minutes.
In a skillet, cook ground beef with chopped onion and minced garlic over medium heat until browned. Season with salt, black pepper, and Italian seasoning.
Add tomato sauce to the beef mixture and simmer for 5 minutes until combined and heated through. Remove from heat.
Roll out the chilled dough into rectangles about 6×8 inches.
Place a portion of the beef mixture on one half of each dough rectangle, then sprinkle with shredded mozzarella cheese.
Fold the dough over to enclose the filling and seal the edges by pressing firmly.
Brush the tops with egg wash for a golden finish.
Place hot pockets on a baking sheet lined with parchment paper.
Bake for 20-25 minutes or until golden brown and crispy.
Let cool slightly before serving, garnished with fresh basil.