Preheat the oven to 450°F (230°C). Lightly spray a 9 x 12 baking dish with non-stick spray.
In a shallow bowl, combine the seasoned breadcrumbs and grated Pecorino Romano (or Parmesan).
In another bowl, whisk together the olive oil, lemon juice, and a few grinds of black pepper to make the lemon oil mixture.
Lay one chicken cutlet flat on a cutting board. Spread about 1 tablespoon sun-dried tomato bruschetta over the center, then add 1 tablespoon shredded mozzarella, 1 tablespoon chopped spinach, and 2–3 slices of red onion.
Roll the cutlet tightly around the filling and place seam-side down. Repeat with the remaining cutlets and filling.
Dip each roll into the lemon oil mixture, then coat thoroughly in the breadcrumb-cheese mixture. Transfer the rolls to the prepared baking dish or a baking sheet.
Lightly spray the tops with olive oil spray and bake in the preheated oven for about 25 minutes, until golden and cooked through (internal temperature 165°F / 74°C).
For air-fryer cooking: preheat the air fryer to 400°F (200°C). Working in two batches, spray both sides of each roll with oil and cook 12 minutes, turning halfway, until golden and cooked through.