Preheat the oven — Heat your oven to 375°F (190°C) and lightly grease a 9×13-inch baking dish.
Brown the beef — In a large skillet over medium-high heat, cook the ground beef until browned and crumbly. Drain any extra grease.
Add aromatics — Stir in the onion and garlic, cooking until the onion softens and turns translucent, about 3–4 minutes.
Make the sauce — Pour in soy sauce, Worcestershire sauce, brown sugar, sesame oil, and ginger. Stir well and let it simmer for a minute so the flavors blend together.
Combine everything — Mix in the chow mein noodles, water chestnuts, and thawed peas and carrots. Spread evenly into the prepared baking dish.
Create the topping — In a small bowl, coat the crushed chow mein noodles with melted butter, then sprinkle generously over the casserole.
Bake — Place in the oven and bake for 30–35 minutes, until golden and bubbling at the edges.
Rest & garnish — Let the casserole rest for 5 minutes before serving. Add extra crushed noodles or green onions on top for a finishing touch.
