To prepare the veloute, combine the butter, shallots, garlic, bay leaf, and thyme in a large saucepan. Sweat the shallots until translucent. Add the whole mushrooms, reduce to low heat, and cook, stirring for 3 minutes. Add the water, bring to a boil, and cook until mushrooms are tender. Pour the mixture into a blender or food processor, and process until smooth. Pour the veloute back into the saucepan, add the cream, and season with salt and pepper.
To make the sabayon, use a stainless steel bowl over a double boiler. Combine the egg yolks and water and beat for about 10 minutes, until eggs reach a stable foamy consistency. Remove the bowl from the double boiler, stir in the truffle oil, and season with salt and pepper.
To serve, divide the veloute among the bowls. Pour a few tablespoons of the sabayon in the center of each bowl, forming a circle. Finish with a slice of white truffle for each bowl.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Laurent Tourondel, Cello Restaurant