In a mixing bowl, combine full-fat mayonnaise, Greek yogurt, Dijon mustard, Worcestershire sauce, lemon juice, minced garlic, and grated Parmesan cheese. Whisk together until smooth. Adjust seasoning with salt and black pepper to taste. Set aside a portion of the dressing for drizzling over the assembled sandwich.

Using a meat mallet, pound the chicken cutlets to an even thickness of 1/2 inch. Season both sides with sea salt and black pepper.

Prepare three shallow bowls with flour mixture, whisked eggs, and panko breadcrumb mixture for breading.

Dredge chicken cutlet in flour, dip into eggs, then coat with panko. Cook in a skillet with oil over medium heat until golden brown and cooked through.

Slice French baguettes, toast lightly, and spread reserved dressing inside. Toss chopped romaine with dressing, layer on baguette with chicken, and sprinkle with more Parmesan. Press gently and serve.