For the sauce: 1) Add 2 tbsps extra-virgin olive oil to a medium pot on the stove over medium heat. Add garlic, crushed red chilli flakes and chopped onions. Cook 10 minutes, stirring often. Add tomatoes and heat through, 2 minutes. Wilt in the basil and season the sauce with salt and pepper.
For the chicken: 1) Preheat outdoor barbeque or indoor griddle pan to high. Season chicken with salt and pepper and drizzle with extra-virgin olive oil to keep it from sticking to the barbeque.
2) Cook the chicken 3 to 4 minutes on each side and transfer to a foil covered platter to hold. If you are using a griddle pan, cook the chicken in 2 batches if necessary.
3) Preheat the grill to high.
4) Layer the chicken with fire roasted sauce in a casserole dish. Top the casserole with Parmigiano and mozzarella cheese. Brown the casserole under the grill for 3 minutes.