Preheat oven to 375°F. Grease 4 holes of an extra-large muffin pan or one loaf pan.
Beat together eggs, parmesan, milk, and salt and pepper until frothy. Divide between muffin cups or pour all into the loaf pan. Bake for 10-12 minutes, until puffed and set.
Meanwhile, cook the bacon and slice open the ciabatta buns.
Set open buns on a baking sheet. Once eggs are done cooking, remove eggs from pan and arrange one on each bun bottom. Add a slice of cheese on top, then bacon. If eating immediately, put tray in the oven and broil just long enough for cheese to start to melt.
To freeze, top sandwiches with the bun top and then put the tray in the freezer. Once frozen, wrap sandwiches individually. Reheat in the microwave or toaster oven.