Brown in olive oil (on medium-high) for about 4 minutes per side
Removed the chicken from the pan (just place them on a plate)
Reduce heat to medium
Add onion, splash of balsamic (to break up the bits on the bottom of the pan), and garlic
After stirring a bit, til fragrant, reduce the heat to low
Add crushed tomatoes and season well with salt and pepper.
Place chicken back in the pan and cover it to let the steam finish cooking the chicken for about 10 minutes. (Just check by cutting through with a knife.)
After the chicken is cooked, cover each piece in feta or parmesan and top with chopped fresh basil.
Finish by spooning a bit of the tomato sauce on top and serve with your favorite pasta!