Prepare the chicken: Pat the chicken breasts dry with paper towels. Season generously on both sides with salt and black pepper.

Cook the chicken: Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Once hot, add the seasoned chicken breasts. Cook for 6-8 minutes per side, or until the internal temperature reaches 165°F (74°C) and the chicken is cooked through with no pink remaining. Remove from the skillet and let rest on a cutting board for 5 minutes.

Shred or dice the chicken: Once the cooked chicken has rested, either shred it using two forks or dice it into small, bite-sized pieces.

Combine chicken and pesto: In a medium bowl, combine the shredded or diced chicken with the basil pesto. If using, stir in the mayonnaise for an extra creamy texture. Mix well until the chicken is evenly coated.

Warm the tortillas: Lightly warm the tortillas in a dry skillet over medium heat for about 15-20 seconds per side, or microwave them for 15-20 seconds, until they are soft and pliable. This makes them easier to roll without cracking.

Assemble the wraps: Lay each warmed tortilla flat. Spread a portion of the pesto chicken mixture down the center of each tortilla. Top with a quarter of the shredded mozzarella, romaine lettuce, halved cherry tomatoes, diced cucumber, and thinly sliced red onion.

Roll the wraps: Fold in the sides of the tortilla, then tightly roll it up from the bottom, creating a secure wrap. Slice each wrap in half diagonally before serving.