Marinate chicken breasts in Italian Dressing for several hours.: The aroma will become tangy and herb forward as the Italian Dressing works into the meat, slightly softening fibers and transferring savory notes. You should notice the surface become glossy and faintly fragrant, which signals the marinade is doing its job. This short acidic soak improves overall juiciness and depth of flavor, and it helps the final dish taste cohesive. A common mistake is marinating in metal containers that can react with acidic dressings, so use glass or plastic. If the chicken stays in the dressing for too long, the texture may become slightly mealy, so avoid overnight marinating beyond several hours.
Preheat oven to 350.: As the oven warms, you will hear the faint hum of heating elements and smell the dry heat filling the kitchen, which primes the baking environment. A consistently preheated oven ensures even cooking and prevents the outside from overcooking while the center catches up. Use an oven thermometer if your appliance tends to run hot or cold, because inaccurate temps are a frequent source of uneven doneness. If you place the chicken into an oven that's not fully preheated, it may cook unevenly and yield variable texture.
Combine cubed tomatoes, olive oil and basil in a bowl and mix well.: When you toss these together the tomato juices will mingle with the olive oil , releasing a bright, herb scented steam when stirred. The look should be glossy, with basil threads and tomato pieces evenly coated. Let the mix sit briefly so flavors marry, and taste for balance between acidity and oil. A pitfall to avoid is adding too much oil which mutes the tomato brightness; start with the smaller amount and adjust. If tomatoes feel watery, drain a little before assembly to prevent soggy topping.
Place chicken breasts on a foil-lined cookie sheet. Add desired amount of mozzarella cheese on top of the chicken breasts (we added about a few TB to each breast). Top with a few tablespoons of the tomato mixture.: As you arrange the pieces, the chicken should look evenly spaced to allow hot air circulation, and the foil makes cleanup effortless. When you add the shredded mozzarella cheese , it should sit atop the meat in an even layer, beginning to melt and show glossy edges once baked. Spoon a few tablespoons of the tomato mix so it rests on the cheese and does not overwhelm the meat. Visual cues to watch for are tidy portions and no pooling of tomato juices beneath the chicken . A common mistake here is piling on too many tomatoes which can steam the cheese rather than letting it melt and brown gently.
Bake for 40-45 minutes.: During baking you will notice the kitchen filling with a warm, savory aroma, and if you peek you might see the cheese transform from stringy to softly golden and the tomato topping bubbling gently at the edges. The internal texture of the chicken should register as juicy and firm when done, typically reaching a safe internal temperature. Allowing the chicken to rest a few minutes after baking helps the juices redistribute so slices remain moist. A frequent error is slicing immediately from the oven which lets flavorful juices spill onto the pan, leaving the meat drier.