Prepare the Eggs: In a medium-sized bowl, whisk together the eggs, egg whites, and water until well combined.
Scramble the Eggs: Set a large skillet over medium heat and coat it with cooking spray. Pour the egg mixture into the skillet. Cook, occasionally scraping the pan, until the eggs are scrambled and just set. Season with salt and pepper.
Assemble the Quesadilla: Heat a medium-sized skillet over medium-high heat. Place 1 tortilla in the pan. On half of the tortilla, layer ¼ of the grated cheese, scrambled eggs, a few shakes of hot sauce, avocado slices, and spinach leaves.
Cook the Quesadilla: Fold the tortilla over to form a half-circle. Press down with a spatula as the cheese melts to help seal the quesadilla. Cook until the bottom is golden brown, then flip and brown the other side.
Serve: Remove the quesadilla from the skillet, cut it into thirds, and garnish with minced parsley if desired. Serve hot. Repeat the process with the remaining tortillas and filling ingredients.