In a large mixing bowl, whisk together the ranch dressing mix, black pepper, olive oil, lemon juice and garlic powder.
Add in the chicken, toss well to coat the chicken. Marinade the chicken for at least 30 minutes or up to 4 hours.
Preheat the grill over medium high heat (400 degrees F) and rub the grill grates with oil to prevent the chicken from sticking onto the grill.
Place the chicken directly on the grill grates and grill the chicken for 4-6 minutes on each side until the chicken reaches an internal temperature of 165 degrees F. Make sure that the chicken does not get over cooked based on the thickness of your chicken.
Move the chicken to a separate plate to rest for at least 5 minutes.
Then it's time to assemble the sandwiches. Spread the ranch dressing on the bottom side of the hoagie roll.
Top with lettuce, tomato, chicken breasts (2 per sandwich), avocado slices, cheese and 2 bacon slices per sandwich. Drizzle more ranch dressing on top if you prefer, then top with the top part of the hoagie and the sandwich is ready to serve and enjoy!