Put the vinegar, lemon juice, garlic, egg yolk, mustard, Worcestershire sauce, anchovies, and pepper in a blender and blend until well mixed.
With the machine running, add the olive oil, at first by drops and then, as the mixture emulsifies, in a thin, steady stream until all the oil is incorporated.
Pulse in 3/4 of the Gorgonzola and the Parmesan. Scrape into a bowl. Fold in the remaining Gorgonzola. Cover, and refrigerate until needed. You should have about 1 1/3 cups. (The dressing keeps, refrigerated, for 2 to 3 days.)
Place the shredded romaine and iceberg in a large bowl and toss with the dressing. Lay the romaine leaves on a platter. Place a few tablespoons of the salad onto the leaves and garnish with additional cheese.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.
Recipe courtesy of Michael Chiarello