Heat oven to 200C/180C fan/gas 6. Cut a slit in the side of each chicken breast, then use your finger to make a pocket.
In a small bowl, mix together the lactose free butter, half the lemon zest, Parmesan, capers, chili flakes and some seasoning. Push the mixture into the pockets, then secure each opening with a toothpick.
Put the chicken in an ovenproof dish, drizzle over 1 tbsp of the oil and season. Bake for 15-20 mins until cooked through.
Meanwhile, make the sauce. Heat the remaining oil in a saucepan, add the garlic infused oil, sugar and tomatoes, season and simmer for 10 mins more until thickened.
Spoon onto 2 plates, top with the chicken and scatter over the parsley and remaining zest. Serve with potatoes, if you like.