In a skillet brown ground meat. Drain excess oil. Add green pepper and onion and cook until tender. Add drained black beans, canned green chiles, salt, pepper, oregano, and garlic powder and set aside.
In a small bowl combine eggs and milk and whisk together.
In a 9 X 13 baking pan, butter the bottom of the pan. Lay the green chiles flat to form a bottom layer in the pan. Top with a layer of the meat/bean mixture. Sprinkle the cheeses over the meat layer.
Add another layer of open, flat green chiles, meat, and another layer of cheese. Reserve some cheese for later.
Pour egg/milk mixture over the top of the layers.
Bake at 350° for 30 minutes. Sprinkle additional cheese over the top and return to oven until cheese melts.
Remove from oven and let it sit for 5 minutes before serving. Garnish with chopped cilantro and serve with sliced avocados.