01 - Preheat oven to 400°F or prepare a medium-hot grill.
02 - Combine olive oil, Cajun seasoning, smoked paprika, garlic powder, salt, and black pepper in a large mixing bowl. Mix thoroughly.
03 - Add chicken breasts to the marinade and turn until evenly coated.
04 - Add the sliced bell peppers, zucchini, red onion, and baby potatoes to the bowl. Toss to coat vegetables with marinade.
05 - Cut 4 large sheets of heavy-duty aluminum foil, each about 12 x 16 inches.
06 - Evenly distribute the vegetable mixture onto each foil sheet, then place one chicken breast atop each pile of vegetables.
07 - Fold foil tightly over the chicken and vegetables to create sealed packets.
08 - Arrange packets on a baking sheet or directly on the grill. Cook for 25 minutes, until chicken reaches an internal temperature of 165°F and potatoes are tender.
09 - Carefully open packets to release steam, sprinkle with chopped fresh parsley, and serve with lemon wedges if desired.