Preheat oven to 350ºF
In a large cast-iron skillet or oven-safe pan, over medium-high heat, melt butter. Add onions and sauté for 5-7 minutes, until tender. Add garlic and sauté for 1-2 minutes, until fragrant.
Stir in beans, dust with taco seasoning and stir in skillet sauce, until combined.
Create 4 wells, evenly spaced, with your spoon or spatula in the bean mixture. Crack eggs into wells.
As egg whites start to cook through at the bottom of the pan and become solid, remove from the heat and add to the middle rack in the oven to bake for 5-8 minutes. Until the egg whites have set and the yolk remains liquid, or until desired firmness.
Remove pan from oven and garnish with a few spoons of salsa, avocado, tomato, scallion, cilantro, and cheese.