Preheat your oven to 375°F (190°C). Dice the onion, chop the bell pepper, and shred the cheeses. Drain black beans and set aside.

In a skillet over medium heat, brown the pork sausage for 8 to 10 minutes until no pink remains. Drain excess fat if necessary.

Add diced onion to the skillet and cook for 2 to 3 minutes. Then, add the bell pepper, black beans, green chilies, chili powder, and cumin, sauté for another 2 to 3 minutes.

Remove from heat and stir in the hash browns, cheddar, and mozzarella until well combined.

In a bowl, whisk eggs and heavy cream, adding a pinch of salt and pepper. Mix until smooth.

Butter the baking dish, layer half of the sausage mixture, pour half of the egg mixture, add remaining sausage, and finish with the last of the egg mixture.

Bake uncovered for 40 to 50 minutes until set with a slight jiggle in the center.

Cool for 10 to 15 minutes before serving, topped with sour cream, salsa, and sliced avocado.