Preheat oven to 450 degrees. Heat butter in skillet. Add onion and cook over medium heat until translucent, 5 minutes. Add the garlic and cook for one minute. Increase heat to high; add tomatoes and cook until liquid is almost evaporated, 5-10 minutes. Add cream and bring to boil; boil until slightly thickened, approximately 3 minutes. Stir in basil, salt and pepper. Arrange chicken in shallow baking dish; pour sauce on top. Bake for 20-25 minutes or until chicken is done.