Preheat the oven to 350°F.

In large oven-safe skillet, heat the butter over medium heat. Add the ground beef, onions, and taco seasoning and cook until the beef is cooked all the way through, about 7 minutes. Add the tomato sauce and stir well to combine.

In large bowl, mix together the eggs, broth, cheeses, garlic, cilantro, salt, and pepper.

Add the egg mixture to the beef mixture and stir to combine. Cook over medium heat for 3 minutes, until the eggs are just slightly set, stirring continuously.

Place the skillet in the oven and bake for 27 minutes, or until the eggs are cooked through in the center. Remove from the oven and let rest for 3 minutes, then slice and serve. If desired, garnish with fresh chives and/or cilantro and serve with salsa. Store leftovers in an airtight container in the fridge for up to 3 days.

Reheat in a 350°F oven for 3 minutes or in the microwave for 30 seconds, or until heated through.