Start by preheating your oven to 450°F so it's nice and hot when the packets go in. While that heats up, cut four sheets of heavy-duty foil, each about 12x12 inches. Having everything ready before you start mixing keeps the whole process moving quickly.
In a large bowl, combine your cubed chicken, chopped peppers, zucchini, onion, and minced garlic. Drizzle in the olive oil, then add the paprika, Italian seasoning, garlic powder, onion powder, salt, and pepper. Toss everything together until every piece is evenly coated in seasoning.
Divide the seasoned chicken and veggie mixture evenly among your four foil sheets, placing it in the center of each one. Fold the sides of the foil up and over the filling, then crimp the edges tightly so no steam can escape while baking.
Place the sealed packets on a baking sheet and slide them into the oven. Bake for 20 to 25 minutes, until the chicken reaches 165°F internally and the vegetables are tender. I always check one packet with a thermometer just to be safe.
Once out of the oven, carefully poke a small hole in the top of each packet to let the steam escape before opening. Open the foil away from your face, taste for extra salt or pepper, then top with parsley and red pepper flakes if you like a little extra flavor.