Heat the water bath of an immersion circulator to 151°F.
In a vacuum bag, seal egg yolks. Cook sous vide 1 hour 20 minutes.
In a food processor, add yolks and cayenne. Turn on low speed and stream in half of oil.
Add ¼ cup water and remaining oil until completely emulsified.
Add an additional ¼ cup water, or more, until desired consistency is reached. Reserve.
In a bowl, combine 1¼ quarts Mayonnaise, onion, garlic, and buttermilk. Season with salt and pepper to taste.
Transfer French Onion Ranch to a small serving bowl.
Spoon crème frâiche over top; garnish with caviar and chives.
