Preheat the oven to 425 degrees.

Heat olive oil over medium heat in a large cast iron skillet or other non-stick, oven proof skillet.

Add potatoes, toss to coat with the oil, cover the skillet, and cook for 10 minutes.

Meanwhile, chop the onion, bell pepper, and zucchini into bite sized pieces. After the 10 minutes are up, uncover the skillet and stir in the onion and pepper. Turn the heat up to medium high and cook for another 10-12 minutes or until potatoes are softened and vegetables are golden brown.

Stir in the zucchini and spinach and cook until spinach is wilted, about 2 minutes. Sprinkle mixture with garlic salt, salt, and black pepper. Make 4 small wells in the mixture and crack an egg into each one. Immediately place the skillet in the preheated oven and bake until whites are set but centers are still runny, 5-7 minutes.

Remove the skillet from the oven, toss the grape tomatoes and chives on top, and serve.