Bring a large pot of salted water to a boil. Add the whole wheat penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Drain and rinse under cold water to cool. Set aside.
While the pasta cooks, preheat a grill pan or skillet over medium-high heat.
Pat the chicken breasts dry with paper towels. Rub both sides with olive oil, salt, and black pepper.
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 bite-sized strips.
In a medium bowl, whisk together the Caesar dressing, Greek yogurt, lemon juice, Dijon mustard, minced garlic, Worcestershire sauce, and black pepper until smooth and creamy.
In a large mixing bowl, combine the cooled pasta, chopped romaine lettuce, sliced chicken, and grated Parmesan cheese.
Pour the dressing over the salad and toss gently to coat all ingredients evenly.
If desired, add halved cherry tomatoes for garnish and toss lightly.
Serve immediately or refrigerate for up to 2 hours before serving for a chilled pasta salad.