Preheat oven to 350° F. Spray a 13x9x2-inch baking pan with vegetable cooking spray.
In a large fying pan, cook sausage, green pepper, red onion, mushrooms, garlic salt, and black pepper over medium-high heat. Cook until sausage is browned and vegetables are soft, about 7 minutes. Set aside to cool.
In a separate bowl, whisk together eggs and milk until well combined; stir in tomatoes. Pour over sausage mixture.
Space biscuits evenly apart on bottom of baking dish. Pour sausage and egg mixture over biscuits and sprinkle evenly with cheddar cheese. Bake for 25 to 30 minutes, uncovered, or until biscuits are cooked and cheese is melted and golden brown. Remove from oven and let cool for 5 minutes before serving. Garnish with chopped parsley.Servings: 8