1/2 cup finely grated Parmigiano-Reggiano
2 tablespoons roasted garlic
2 tablespoons sherry vinegar
1 tablespoon Dijon mustard
6 white anchovies
1 egg yolk
1 1/4 cups canola oil
Combine the cheese, roasted garlic, vinegar, mustard, anchovies and egg yolk in a food processor.
Blend until a smooth paste has been formed.
If necessary, add 2 tablespoons water to ensure it is a smooth paste, and not clumpy. With the machine running, emulsify the oil into the paste in a steady stream. Add more water or vinegar as necessary, depending on how loose or acidic you prefer the dressing.
NOTE In the comments of the original there is a suggestion of adding 1/2 of a lemon.