1. Preheat oven to 425 degrees Fahrenheit and place a rimmed quarter sheet pan in the oven to heat up.
2. In a skillet, heat up the olive oil over medium-high heat. Cook the scallions for a minute, and then add the mushrooms and asparagus into the pan. Cook for five minutes and then set aside.
3. In a bowl, whisk the eggs. milk, salt and pepper. Fold in the cheese. Remove the baking sheet from the oven (careful, it’s hot!) and spray it with cooking spray. Pour the egg mixture into the sheet pan and top with cooked scallions, mushrooms, and asparagus.
4. Bake for 12 to 15 minutes. Cut into squares and serve.