Place your cast iron skillet or heavy-bottomed pan over medium-high heat and add the olive oil or butter.

Cut the potatoes into cubes, keeping the skin on for flavor. Rinse them quickly and pat dry. Add the potatoes to the hot skillet. Let them settle and brown on one side without stirring immediately to get a nice crust.

Season the potatoes with all-purpose seasoning, a generous pinch of salt, and fresh ground black pepper. Stir to coat and flip the potatoes so the uncooked sides hit the pan. Cook until they are tender and golden brown, approximately 10-12 minutes.

Add the diced onions, red bell peppers, and sliced mushrooms to the skillet. Sauté with the potatoes until the onions are translucent and the mushrooms are browned, about 3-5 minutes.

Add the fresh spinach on top of the mixture and stir gently until it just begins to wilt, about 1 minute.

Create four indentations (wells) in the vegetable mixture with a spoon. Crack an egg into each space. Season the eggs lightly with salt and pepper.

Cover the skillet with a lid or foil. Cook until the egg whites are set but the yolks are still runny, or to your desired doneness.

Sprinkle the shredded cheddar cheese over the entire skillet. Place the lid back on briefly, off the heat, to allow the cheese to melt from the residual heat.

Top with sliced green onions, avocado, and parsley. Serve immediately!