Preheat a grill to medium-high heat or about 600 degrees F (315 degrees C) at the GrillGrate surface.
In a large bowl combine the garlic, Italian herbs, olive oil, and pesto.
Slice each chicken breast in half to create two even chicken cutlets/steaks.
Add the chicken to the pesto seasoning blend and toss through to create an even coating of the seasoning.
Arrange the chicken evenly on the hot GrillGrates avoiding crowding. Close the lid of the grill and allow to cook for 7 to 8 minutes.
Topping
Heat the marinara pasta sauce.
Open the grill then turn the chicken breast. Immediately add the heated marinara sauce, then top with the mozzarella slices and sprinkle with Parmesan cheese. Close the BBQ lid and reduce the heat to medium-low or about 350 degrees F (180 degrees C) at the GrillGrate surface.
The chicken is ready when the internal temperature is at least 165 degrees F (71 degrees C) and the cheeses melted. If overcooked the cheese can melt too much and slide off the chicken, being lost forever.