Preheat the oven to 220°C. Line a large baking tray with foil and spray with low-calorie cooking spray. Place the tomato halves on the baking tray in a single layer, cut-side up.
Spray the tomatoes with low-calorie cooking spray and season with salt and black pepper. Place in the preheated oven and roast for 20 minutes until they have wrinkled a little and are starting to brown slightly around the edges. Remove from the oven and set aside.
While the tomatoes are roasting, spray a large frying pan with low-calorie cooking spray and place over a medium heat. Add the onions, garlic and peppers and fry gently for 5 minutes until they have softened a little.
Add the chicken breasts and cook for 4 minutes, turning halfway through. The chicken breasts should be lightly golden.
Add the passata, basil, oregano, tomato puree, balsamic vinegar, Worcestershire sauce, white wine vinegar, sweetener and mustard. Stir in and simmer, uncovered for 10 minutes. Turn the chicken breasts over and loosely cover with a lid or with kitchen foil.
Simmer for a further 10 minutes, or until the chicken is cooked and white throughout. Use a small sharp knife to cut into the thickest part of the chicken to check. There should be no pinkness and the juices run clear.
Remove the frying pan from the heat and stir in the cream cheese until completely blended. If the sauce is too thin, continue to simmer for a bit longer until the sauce has reduced and thickened to your liking. If the sauce is too thick, stir in a little water.
Stir the roasted tomatoes into the sauce and season to taste with salt and black pepper, if needed. Serve with an accompaniment of your choice.