Preheat a grill or grill pan on medium heat, season both sides of the chicken with a pinch of salt and pepper and cook about 5 - 7 minutes on both sides until it is no longer pink inside and reaches an internal temperature of 160 degrees. (cook time depends on how thick the breast is.) Once cooked thinly slice the chicken.
In a blender or food processor pulse the mayo, basil, and garlic until smooth.
Spread the mayo on the bread and layer with arugula, tomato, chicken, and fresh mozzarella on a roll and serve with pickles on the side.