01 - Set a grill pan or large skillet over medium-high heat and allow it to come to temperature.
02 - Coat the chicken breasts evenly with olive oil, garlic powder, smoked paprika, salt, and black pepper. Place onto the hot grill pan and cook for 6 to 7 minutes per side until the internal temperature reaches 165°F and juices run clear. Transfer to a plate and rest for 5 minutes before slicing thinly against the grain.
03 - In a mixing bowl, combine the shredded mozzarella, cheddar, grated Parmesan, minced garlic, mayonnaise, and chopped parsley. Stir until all ingredients are evenly incorporated into a thick, cohesive spread.
04 - Lay each flour tortilla flat on a clean work surface. Divide the garlic cheese mixture into four equal portions and spread each across the center of a tortilla. Layer with baby spinach, sliced tomatoes, red onion if using, and the sliced chicken breast.
05 - Fold the left and right sides of each tortilla inward over the filling, then roll tightly from the bottom edge to form a secure, enclosed wrap.
06 - Wipe the skillet clean and return it to medium heat. Place each wrap seam-side down onto the pan and grill for 2 to 3 minutes per side until the exterior is golden brown and the cheese inside has fully melted.
07 - Slice each wrap in half diagonally and serve warm.