This recipe was given to me by my sister, who had come across it somewhere. I have changed it to be heart healthier by reducing the cheese and increasing the veggies. You can also add sliced mushrooms, and most any kind of fresh vegetable, such as cauliflower. I serve it over egg noodles, drizzled with the juices, or with rice pilaf. It's a complete meal and is very tasty and satisfying. Sometimes I use mild cheddar, sometimes sharp, depending on what is in the fridge. You can also replace the mozzarella with another white shredded cheese, but I have found that the texture is better if you use the mozzarella.
Combine about 1/2 cup of cheddar and 1/2 cup of mozzarella in a medium bowl. Add broccoli florets and chopped tomato and mix thouroughy.
Place a good handful of cheese and veggie mixture in each prepared chicken breast and roll up, and repeat until all chicken is stuffed. Place seam side down in a casserole dish ( I use a pie pan). Drizzle melted margarine or butter over breasts, then top the breasts with remaining cheese mixture. Sprinkle with paprika and bake at 350 for about 45 minutes to an hour or until chicken is done and cheese is nice and brown.