You are not going to find a better blue cheese dressing than this.
Really - you won't.
Once you have this you will never go "back to the bottle" and will sneer in mild disappointment at every restaurant that has blue cheese dressing as an option.
I got this from my buddy Jim who in turn got it from a cookbook by Paul Prudhomme, whom I had the honor to meet for all but 14 seconds at the 2008 Fancy Food Show.
"Hi Chef Paul - I'm a big fan of your blue cheese dressing."
"Thank you. I have a new one that you should try."
"Really? Great! I'd like to know..."
And by then he was talking to some other schmuck and giving his autograph.
I've modified it a tinge (more garlic and chili powder). Also make this eight hours or even a day before you need it: it's much better the second day as the flavors have had a chance to blend together.
½ large white onion, coarsely chopped
5 garlic cloves, coarsely minced
½ cup buttermilk (lowfat or fat free - doesn't matter)
2 cups canola oil
6 ounces of crumbly blue cheese (typically Danish)
1 TSP ground white pepper
1 TSP table salt
½ to 1 TSP cayenne pepper
¼ TSP chili powder
In a food processor add the onion and garlic and puree until smooth, about one minute. Add the egg and salt and process for 30 seconds, then pour in the buttermilk while the processor is running.
With the thing still whirling away, slowly pour in the oil in a continuous stream. Add 2 ounces of the blue cheese and white pepper and process for another 15 seconds.
Pour the dressing into a glass bowl (if you use plastic it will wreak of blue cheese forever). Add the remaining blue cheese and the cayenne and chili powder.
This comes out pleasantly spicy with a tinge of smokiness. You can leave the cayenne and chili out, or reduce the amounts, and you still have a great dressing.
Serve on a wedge of cold iceberg with bacon bits, chunks of tomato and red onion. Good times, good times.