In a small bowl, whisk together the egg product, garlic, anchovy paste, mustard, Worcestershire sauce and lemon juice. Slowly add the olive oil in a steady stream, whisking the whole time. Stir in the Parmesan and season with salt and pepper.
In a large bowl, toss the dressing with the lettuce and spinach until well coated. Add the croutons and toss to combine. Divide the salad onto 4 plates and top each plate with grilled chicken slices.