In the Netherlands celeriac is an under-estimated vegetable. Indispensible in the traditional peasoup, but that's it. I love it on its own for its naturally sweet, gentle taste.
Cut the bulb in thick slices and peel with a sharp knife. Dice the wheels (to prove that the quadrature of the circle is after all possible). Plunge in cold water to minimize the discolouring. Boil in salted water until tender. Serve with a cheese sauce: just stir in crème fraîche with grated old Gouda or Cheddar. Grate some nutmeg over it. That's all!
In France celeriac is sold as salad in charcuteries. Grated raw, and mixed with a creamy remoulade. Dutch butchers have followed suit.