Preheat oven to 300 degrees and prepare a large and deep ovenproof frying pan with nonstick cooking spray. Heat pan over medium heat until hot.
Beat eggs and combine with milk. Pour into pan, and as eggs begin to set, gently pull the eggs across the pan with an inverted turner, forming large soft curds. Continue cooking — pulling, lifting, and folding eggs — until thickened but not completely done. Do not stir constantly.
Take off burner and stir in rice, mushrooms, bell pepper, onion, ham, salt, and pepper. Mix well. Sprinkle with cheese and top with diced tomatoes and parsley.
Place uncovered pan in oven and bake for 15 minutes. Eggs will finish cooking. Let sit for 5 minutes to set, then cut into 6 pie-shape portions and serve hot.