Slice each large chicken breast in half lengthwise to make 4 thin cutlets.
Place the cutlets in a large zip-top bag and add 1/2 cup Tony Chachere's 30-Minute Chicken Marinade; turn the bag to coat the chicken evenly and marinate for 30 minutes.
While the chicken marinates, combine mayonnaise, sour cream, lemon juice, Worcestershire sauce, 1/4 teaspoon Tony Chachere's seasoning, and minced garlic in a medium bowl; whisk until smooth and adjust seasoning to taste.
Tear the romaine into bite-size pieces and place in a large salad bowl; grate the Parmesan and measure the croutons.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Remove chicken from the bag, discard marinade, and add the cutlets to the hot pan in a single layer.
Cook the chicken about 5 minutes per side, until nicely seared and cooked through; transfer to a plate and let rest a few minutes, then slice into strips.
Drizzle the dressing over the romaine gradually to taste, toss to coat, sprinkle with grated Parmesan and croutons, then top with the sliced Cajun chicken and serve immediately.
