1. Preheat the oven to 350°F (180°C).

2. In a skillet, cook the ground beef over medium heat until browned and cooked through. Drain off any excess fat.

3. Add the green chilies to the skillet and sauté briefly.

4. Remove the skillet from the heat and season the ground beef with salt and pepper.

5. In a bowl, mix together the cornbread mix, eggs, and milk until a smooth batter forms.

6. Pour half of the batter into a greased casserole dish and spread it evenly.

7. Spread the cooked ground beef evenly over the batter.

8. Pour the remaining batter over the ground beef and smooth it out.

9. Bake the casserole in the preheated oven for about 25-30 minutes, until the cornbread is golden brown.

10. Remove the casserole from the oven and let it cool slightly.

11. Garnish the casserole with shredded lettuce, diced tomatoes, and grated cheese.

12. Serve the Mexican Cornbread Casserole warm.