Caesar Dressing: in a bowl, add in your finely minced garlic, anchovies, egg yolk, lemon zest + juice, mustard and whisk well until combined (try to break up the anchovies to small pieces). While whisking, slowly drizzle in your vegetable oil until you have a thick sauce. Grate in the parmigiano and season with salt + pepp to taste. Set aside
Breaded chicken: Slice your chicken breast into 2 pieces length-wise. While working with 1 piece at a time, cover the chicken with a piece of plastic wrap and using a meat tenderiser, flatten out the chicken into a thin even piece. Repeat with the other piece. Season the chicken with salt and pepp.
Add your breadcrumbs onto a plate and mix in the parsley, onion powder and garlic powder. Prepare your breading station. Working with 1 piece of chicken at a time, place the chicken into your flour and cover it well. Transfer the chicken to your beaten eggs and cover it well. Transfer the chicken to your seasoned breadcrumbs and press it in well. Repeat with the 2nd piece.
Bring a pot of oil to frying temperature (180C/ 350F). Carefully drop in 1 piece of breaded chicken at a time and fry for 4-6 minutes, depending on the thickness of the chicken and flipping halfway, or until golden brown. Place on a wire rack to drain.
Assemble: cut your loaf in half and lightly toast. Dress your lettuce leaves with the caesar dressing (you don't have to use up all the dressing! just enough). Place a tbsp of dressing onto your bread and spread it out evenly. Top with a piece of breaded chicken, the dressed lettuce leaves and extra grated parmigiano. Close the sandwich and enjoy!