Preheat the oven to 400°F. Line a baking sheet with aluminum foil and lightly grease it with cooking spray. (You can also use parchment paper)
Add potatoes to the pan and drizzle with some olive oil and season with garlic salt and pepper. Bake for 10 minutes. Add beaten eggs to a third bowl.
Remove from oven and add the remaining vegetables and sausage slices.
Drizzle with the remaining olive oil and seasonings. Toss to coat.
Bake for 20 minutes.