In a large bowl, mix a dozen eggs, milk, salt, pepper and onion powder until well blended.
Pour egg mixture into a nonstick Pampered Chef brownie pan for individual squares or you can pour the whole batch into a greased cookie sheet.
Bake eggs at 350 degrees until cooked through- about 8 minutes.
While eggs bake, cook the bacon and drain grease.
Cut 12 sheets of aluminum foil big enough to wrap around 1 sandwich.
When eggs and bacon are ready, assemble the ciabatta sandwiches with 1 egg, 1 piece of bacon and 1 slice of cheese.
Wrap each sandwich in foil and refrigerate up to 5 days. You can write the type of sandwich and date if you are making different types.
To reheat, put the whole sandwich in the air fryer and bake for approx 2 minutes at 350 degrees. If you don't have an airfryer, wrap sandwiches in plastic wrap or parchment paper and reheat in the microwave. Do Not Microwave Foil!