Preheat oven to 375°. Lightly grease baking dish, then layer spinach leaves, white parts of scallions, and dried parsley in bottom of baking dish.
In large skillet over medium heat, cook breakfast sausage until browned and crumbled.
While sausage cooks, whisk together eggs, egg whites 1/2 and 1/2 creamer, garlic powder, salt, and pepper in large mixing bowl. Once ingredients are fully combined, add in shredded cheese.
Evenly add cooked sausage on top of spinach in baking dish. Pour egg mixture over sausage, making sure to distribute mixture as evenly as possible across baking dish. You will think there is not enough mixture but as it cooks the spinach shrinks.
Bake 20 to 25 minutes or until casserole is firm and eggs are cooked through. Remove from oven and sprinkle green parts of scallions on top.
Let stand 5 minutes. Cut into 12 even pieces and serve.
Notes
Sausage - I used 1/2 pound medium Jimmy Dean sausage and 1/2 pound hot Jimmy Dean sausage. It depends on how spicy you like things.