Preheat broiler to low heat. Place the bread on a sheet pan and toast on one side for about 1 minute. Flip and place mozzarella cheese on the opposite side and broil again for 1 minute until melted.
Meanwhile in a small food processor (or just finely chop and mix), combine the basil and mayonnaise (and parsley if using) and process until almost smooth.
Spread pesto mayo on the other side of the bread. Top with turkey, roasted red peppers, spinach or lettuce, and freshly cracked pepper.
Notes
Calorie quotes for one full, large, sandwich.
If you have extra fresh parsley on hand, I like to add a small handful of fresh leaves to the processor (about 2 tablespoons).