For the salad dressing: Put the mayonnaise, buttermilk, sour cream, Parmesan, balsamic, Worcestershire, anchovies, garlic and some salt and pepper into a blender or food processor and pulse the processor or blend on low speed for several seconds. Adjust the consistency if needed with a little extra buttermilk. Refrigerate the dressing for a few hours (it just gets better!) before using it on the salad.
For the croutons: Preheat the oven to 400 degrees F.
Throw the bread cubes onto a baking sheet and toss them in the olive oil and some salt and pepper. Sprinkle on half of the Parmesan, toss, sprinkle on more and toss again. Bake, tossing again halfway through, until crisp and golden brown, 12 to 15 minutes. Set aside to cool.
For the salad: Throw the green leaf and romaine lettuce into a bowl. Add some dressing, and give it a good initial toss, just so you can evaluate how much more dressing you need. Add more dressing to taste. Add the cooled croutons. Toss gently and serve.