Preheat oven to 425 degrees F (220 degrees C). Grease a shallow 2-quart baking dish.

Heat a skillet over medium heat; cook and stir salami, artichokes, tomatoes, and mushrooms until heated through, about 4 minutes. Transfer salami mixture to baking dish.

Whisk eggs, milk, green onions, garlic, basil, onion powder, salt, and black pepper in a large bowl; pour eggs over salami mixture. Sprinkle with mozzarella cheese and Parmesan cheese.

Bake until eggs are set and cheese is melted, about 20 minutes.