In a small bowl, combine all ingredients for the dry seasoning mix. You should yield 3 tablespoons in total (about 0.8 ounces).
In a large measuring cup, add the oil, 2 tablespoons of balsamic vinegar, water and 2 tablespoons of the dry mix. Whisk until combined.
Place the chicken breasts in the baking dish. Pour the marinade on top. Cover and refrigerate at least 30 minutes prior to baking.
Preheat oven to 400 degrees.
Uncover the chicken. Do NOT drain the marinade. Bake for 30-35 minutes or until the internal temperature reaches 160 degrees.
While the chicken is baking, prepare the sauce in a nonstick skillet.
Over medium heat, saute the garlic cloves and shallots in the butter until softened, about 1-2 minutes.
Add the halved tomatoes and saute until blistered, about 2-3 minutes.
Add the remaining 1 tablespoon of seasoning mix and cook an additional 1-2 minutes.
Add the balsamic vinegar and heavy cream and cook 2-3 minutes, stirring continuously.
Remove the chicken from the oven. Nestle the cooked chicken (not the juices) into the prepared sauce. Serve immediately.