Preheat the oven to 400 degrees F. Season the chicken with salt and pepper. Lay out four 12-by-18-inch sheets of foil. Drizzle each sheet with olive oil, then top each with a chicken breast.
Combine the tomatoes, artichokes, olives, capers, 2 minced garlic cloves, 1 tablespoon olive oil, 1/2 teaspoon salt and 1/4 teaspoon red pepper flakes in a bowl; divide evenly over the chicken. Fold up the edges of the foil and seal each to form a packet; set on a baking sheet. Bake until the chicken is cooked through, about 30 minutes.
Meanwhile, combine the remaining 3 tablespoons olive oil, 2 minced garlic cloves and 1/4 teaspoon red pepper flakes, and a pinch of salt in a bowl; spread over the baguette halves and sprinkle with the parmesan and parsley. Bake until the bread is golden around the edges, 8 to 10 minutes. Cut each piece in half.
Open the foil packets and serve with the garlic bread.