Heat olive oil in a skillet over medium heat. Add onion and pepper and cook until just soft. Add garlic, cook 1 minute and turn off heat. Allow to cool enough to handle.

In a large bowl, combine ground chicken, onion mixture, salt, pepper and Italian seasoning by hand. Form into patties.

Preheat grill to medium heat level.

Place burgers on grill and cook about 8 minutes per side, making sure internal temperature reaches 165.

While burgers are cooking, toast your bread on grill if desired and warm marinara.

Just before removing burgers from grill, add a slice of mozzarella cheese to each patty and close the cover , just to melt (about 1 minute).

Serve burgers on toasted bread and top with warmed marinara. Top with fresh basil if desired.