ingredients
directions
For bouquet garni:
Place thyme, parsley and bay leaf in a 5-inch (12.5 cm) square of cheesecloth. Tie corners together with kitchen twine, leaving ends long to tie to pot handle.
Place potatoes and garlic in a large saucepan of cold, well salted water. Bring to a boil. Reduce heat to medium and cook, covered, for about 25 minutes or until fork tender. Drain and mash potatoes with ricer or masher (do not use food processor). Transfer to a bowl.
Meanwhile, in a separate saucepan of boiling, salted water, tie bouquet garni to handle of pot, and immerse it in the water. Add celery root, turnip, garlic, and leeks and cook, over medium-high heat, until tender, about 25 minutes. Drain and transfer to bowl of food processor. Pulse until smooth. Fold into potatoes with cream, butter, horseradish and salt.