Cook the whole wheat penne pasta according to package instructions until al dente. Drain and rinse under cold water to cool. Set aside.
While the pasta cooks, preheat a grill pan or skillet over medium-high heat.
In a small bowl, mix garlic powder, dried Italian seasoning, salt, and black pepper. Rub the chicken breasts evenly with olive oil and then coat with the seasoning mixture.
Grill the chicken breasts for 6-7 minutes per side, or until fully cooked and internal temperature reaches 165°F (74°C). Remove from heat and let rest for 5 minutes.
Slice the grilled chicken into thin strips.
In a medium bowl, whisk together Greek yogurt, mayonnaise, lemon juice, Dijon mustard, minced garlic, Worcestershire sauce, salt, and black pepper until smooth to make the Caesar dressing.
In a large mixing bowl, combine the cooked pasta, chopped romaine lettuce, sliced chicken, grated Parmesan cheese, and Caesar dressing. Toss gently until everything is evenly coated.
Add the whole wheat croutons just before serving to maintain their crunch.
Serve immediately or refrigerate for up to 2 hours before serving for a chilled salad.