Prepare the Bread: Slice the sub roll in half lengthwise. Place both halves on a baking sheet, cut side up.
Layer the Ingredients: On the bottom half, layer the grilled chicken, crispy bacon, and cheese slices.
Toast the Sandwich: Place the sandwich under the broiler for 1-2 minutes, or until the cheese melts and the top half is lightly toasted.
Add Fresh Toppings: Remove from the oven and layer lettuce, tomato slices, red onions, and pickles on top. Season with salt and black pepper.
Drizzle Ranch Dressing: Evenly spread the ranch dressing over the fresh toppings.
Assemble and Serve: Place the top half of the roll over the sandwich, slice in half if desired, and serve immediately.