Preheat oven to 375F. Spray a large baking sheet with olive oil spray.
Slice the ciabatta loaf in half as if you were making a sandwich. Scoop out some of the bread from both sides, but don't get too close to the edges. (Save the scooped bread for another use, such as olive oil tasting or your next meatloaf).
In a large bowl, mix together the diced chicken, corn, and tomato salsa. Scoop evenly into the two ciabatta halves. Top with mozzarella cheese and half the parsley/scallion, if using.
Bake at 375F for 8 minutes, then turn on the broiler and broil for 1-2 minutes until the cheese turns golden brown (watch carefully not to burn it!). Remove from heat and top with additional garnish. Allow to cool for 5 minutes and serve warm with additional salsa, if desired.