WHISK egg product and milk in large bowl until blended. Stir in bread. Add spinach, bacon and 1-1/4 cups cheese; mix lightly.
POUR into 13x9-inch baking dish sprayed with cooking spray; top with remaining cheese. Cover; refrigerate overnight.
HEAT oven to 350ºF. Bake casserole, uncovered, 48 to 50 min. or until top is puffed and golden brown.