Flatten chicken to 1/2-in. thickness. In a large bowl, combine vinaigrette and garlic. Add chicken; turn to coat. Cover; refrigerate 30 minutes. Drain and discard marinade. Sprinkle chicken with salt and pepper.
On a lightly greased grill rack, grill chicken, covered, over medium heat or broil 4 in. from heat 5 minutes. Turn; top with marinara, basil, tomatoes, artichokes, onions and cheese. Cover and cook until chicken is no longer pink and cheese is melted, 5-6 minutes.