In a large mixing bowl, combine chopped chicken, crumbled bacon, and ranch dressing. Mix until all ingredients are well-coated and evenly distributed.

Slice the sub roll in half lengthwise using a serrated knife. Toast the sub roll for about 5 minutes in a preheated oven at 375°F (190°C) until golden brown.

Lay a generous handful of shredded lettuce on the bottom half of the roll. Add an even layer of diced tomatoes.

Spoon the chicken and bacon mixture over the lettuce and tomatoes, spreading evenly to ensure a flavorful sandwich.

Top your sub with shredded cheddar cheese. Broil on high for 1-2 minutes until the cheese is bubbly and lightly golden.

Carefully remove the sub from the oven, close the sandwich, and serve immediately with chips or a fresh salad.