Prepare the Foil Packets:

• Preheat the grill to medium heat or the oven to 400°F (200°C).
• Cut 4 large pieces of heavy-duty aluminum foil, each about 12 inches long.
• Place one sausage in the center of each foil piece.

2. Add Vegetables and Seasoning:

• Surround the sausage with the sliced bell peppers and onion.
• Drizzle olive oil over the sausage and vegetables. Sprinkle with garlic powder, Italian seasoning, salt, and pepper.
• Fold the sides of the foil over the sausage and peppers, then fold up the ends to seal the packet tightly. Ensure that the packet is sealed properly to lock in all the juices and flavors.

3. Cook the Foil Packets:

• Grilling: Place the foil packets on the preheated grill. Cook for 25-30 minutes, turning the packets halfway through, until the sausages are cooked through (internal temperature of 160°F/71°C) and the vegetables are tender.
• Oven: Place the foil packets on a baking sheet and bake in the preheated oven for 25-30 minutes, until the sausages are cooked through and the vegetables are tender.

4. Add Cheese:

• Carefully open the foil packets (watch out for hot steam) and sprinkle the shredded mozzarella cheese and grated Parmesan (if using) on top of the sausage and veggies. Close the foil packet back up and return to the grill or oven for an additional 5 minutes to melt the cheese.

5. Serve:

• Open the foil packets and garnish with fresh chopped parsley before serving. Enjoy your cheesy, savory sausage and peppers!