Wash the lettuce thoroughly and refrigerate until crisp, at least 1 hour or more.
In the meantime, set the oven to 190°C, air circulation, and rack set to the middle position.
Start with the croutons by adding them in a large bowl along with the granulated garlic, ½ tsp of salt and the oregano. Toss them with 2 tbsp of olive oil and place them in an oven-proof dish to be baked until golden brown and crisp, about 15’, tossing them halfway. Remove from the oven and keep aside.
Place the chicken fillets in the same tin dish that the croutons were made and pour over them 2 tbsp of olive oil and season them with the salt and pepper. Place in the oven and cook for about 25’ until golden. Take out of the oven, allow to cool and slice them in 1cm thickness. Keep aside covered.
For the dressing, we place in a glass bowl the yoghurt, the anchovies paste, mustard, honey, Worcestershire sauce, the grated Parmigiano Reggiano cheese, the remaining salt and pepper and whisk well. Add the olive oil and mix well. If too thick then add couple of tbsp of milk to thin it out.
For each serving, take a large bowl and add 3 tbsp of the dressing. Then add into the bowl a handful of the lettuce leaves and toss gently. Remove from the bowl to an individual serving plate, add on top one cut chicken fillet and drizzle with some more of the dressing. Finally, toss on top the croutons and the shaved Kefalotyri. Give a final crack of black pepper and enjoy.