Preheat your oven to 425°F (220°C). Place a wire rack on top of a large baking sheet and lightly spray the rack with nonstick cooking spray or brush with a little olive oil. Using a wire rack helps hot air circulate around the chicken for maximum crispiness.
Slice the chicken breasts in half horizontally or into evenly sized strips about ½ inch thick. Pat the chicken completely dry with paper towels.
Set up the breading station.
In the first shallow bowl, combine the flour with ½ teaspoon salt and ¼ teaspoon black pepper.
In the second bowl, whisk together the eggs and milk until smooth.
In the third bowl, mix the panko breadcrumbs, Parmesan cheese, garlic powder, onion powder, smoked paprika, remaining ½ teaspoon salt, and remaining ¼ teaspoon black pepper.
Bread the chicken. Dredge each piece of chicken in the seasoned flour, shaking off any excess. Dip it into the egg mixture, then press it firmly into the panko mixture until evenly coated on all sides.
Arrange on the baking rack. Place the breaded chicken on the prepared wire rack, leaving a little space between each piece. Lightly spray both sides with olive oil cooking spray or drizzle very lightly with olive oil.
Bake until crispy. Bake for 10–12 minutes, carefully flip each piece, spray lightly again with olive oil, and continue baking for another 10–12 minutes, or until the chicken is golden brown, crispy, and reaches an internal temperature of 165°F.
While the chicken bakes, whisk together the Greek yogurt, ranch seasoning, Dijon mustard, lemon juice, garlic powder, black pepper, and milk (if using) until smooth and creamy. Refrigerate until ready to use.
Heat the flour tortillas in the microwave for 10–15 seconds or warm them in a dry skillet until soft and pliable.
Spread about ¼ cup of the Greek yogurt ranch sauce down the center of each tortilla. Top with ½ cup chopped romaine, ¼ cup shredded cheddar cheese, ¼ cup diced tomatoes, a few slices of red onion, and sliced crispy baked chicken.
Fold in the sides of each tortilla, then roll tightly from the bottom to create a secure wrap.
Toast the wraps (optional but recommended). Place the wraps seam-side down in a dry skillet over medium heat for 2–3 minutes per side, until the tortillas are lightly golden and crisp.
Serve. Slice each wrap in half and serve immediately with extra Greek yogurt ranch sauce for dipping, if desired.