Slice the chicken breasts in half lengthways to give 4 fillets. Season with salt and pepper.
Pan fry over a medium-high heat until it’s golden on both sides. Once golden, remove the chicken from the pan and set aside.
Add in the onion and cook for 4-5 minutes, until it starts to soften. Chuck in the garlic and cook for a further minute.
Pour in the chicken stock, tomato passata and balsamic vinegar.
Stir through the cherry tomatoes and chopped basil. Pop the chicken on top, then lay a piece of mozzarella over each bit of chicken.
Cover with a lid or tin foil, then simmer for 4-5 minutes, until the mozzarella melts.
Dish it up and finish with a drizzle of balsamic glaze.