Heat oven to 350°F. Spray 8-inch square (2-quart) baking dish with nonstick cooking spray. In medium skillet, cook sausage until no longer pink. Drain.
Layer Cheddar cheese, spinach, cooked sausage, mushrooms, onions and pimientos in sprayed baking dish.
In medium bowl, combine eggs and half-and-half; blend well. Pour egg mixture evenly over layered mixture. Sprinkle with Swiss cheese and paprika.**
Bake at 350°F. for 30 to 40 minutes or until knife inserted in center comes out clean. Let stand 5 minutes before serving.