For the croquette filling, pour the chicken stock into a small saucepan and season with salt. Add the chicken thighs, bring to a simmer and poach for 12–14 minutes until the chicken is just cooked. Leave to cool in the liquid. Once cool, remove the chicken and chop into small pieces. Reserve the stock for the béchamel
Make a roux with the butter and flour, stirring all the time, and gradually add the stock until a thick béchamel is achieved. Add the Parmesan, anchovies and garlic, then transfer to a blender and blitz until smooth. Fold through the parsley and chopped chicken and season to taste with salt
Transfer the mix to a tray and place in the fridge until set and firm. When the mixture is set, divide into 12 balls and retain in the fridge
To make the Caesar dressing, blend the egg, vinegar and the mustard until smooth. Add the anchovy, then slowly add the olive oil in a steady stream while whisking, as if you were making a mayonnaise
Once emulsified add the finely grated Parmesan, Worcestershire sauce and adjust the consistency with a touch of warm water and lemon juice. The dressing should be a little loose
Prepare three bowls for crumbing: one with flour, one with egg wash and one with breadcrumbs. Roll the croquettes through each bowl, ensuring that the croquettes are completely covered in the breadcrumbs. Store in a tray of breadcrumbs until needed
Bring a large pan of lightly salted water to the boil and blanch the lettuce and spinach for 2 minutes. Drain well and squeeze out any excess water before transferring to a blender. Blitz until smooth and pass through a fine sieve. Chill in a bowl over ice until needed
Preheat the vegetable oil in a deep saucepan or deep fryer to 180°C
Once the oil is up to temperature, fry the croquettes for 2–3 minutes until golden
To serve, swirl the lettuce purée around the bottom of the plate, add 3 croquettes per portion and a dot of Caesar dressing. Garnish with lettuce leaves, shaved Parmesan, cress and anchovies