Cauliflower combined with cream and eggs is decadently rich, with a mild flavor and a sinfully smooth, silken texture. Here we've added a dash of truffle oil to flavor the flan. Cauliflower and truffles are a match made in heaven, but the oil is optional. The flans can be unmolded or served in their ramekins.
Position a rack in the middle of the oven and preheat to 300 degrees F. Butter the sides and bottoms of 8 1/2-cup oven-proof ramekins and set aside.
Steam the cauliflower florets until they’re very soft and tender, about 15 minutes. Transfer the cauliflower to a food processor and purée the florets with the cream until the mixture is smooth. Add the eggs, salt, truffle oil, pepper, and nutmeg, and process until smooth.
Divide the purée among the 8 prepared ramekins. Set the ramekins in a large baking pan and transfer the pan to the oven. Carefully add very hot water to come halfway up the sides of the ramekins. Bake the flans until they puff up and set — though the center will still wiggle a little when you shake the pan — about 35 minutes.
Remove the ramekins from the water bath and let them rest at room temperature for 10 minutes to set. Run a thin knife around the edges of the ramekins and invert the flans onto warm plates (alternately, you can serve the flans in their ramekins). Serve immediately.