Mystery Egg Bake recipe - from the The Ultimate Donovan Family Reunion Cookbook Family Cookbook

Ingredients

• 16 slices white sandwich bread cut into cubes
• 1 lb sharp cheddar cheese - cut into cubes
• 1 1/2 cup swiss cheese - cut into cubes
• 6 eggs
• 3 cups milk
• 1/2 tsp onion salt
• 1 tsp dry mustard
• 3 cups crushed corn flakes
• 1/2 cup melted butter