Frittata Sandwiches

I don't know why but this was the best frittata I have had in a while. The flavors were a perfect blend. Nothing was over powering. I used the usual vegetables. Onions, Red Pepper, Zucchini, Yellow Squash and Scallions. The cheeses were American, Cheddar, and Parmesan.

 

There was Pancetta on top instead of the usual bacon. Could that have been it?