- Preheat oven to 190°C (375°F). Trim the top off the garlic bulb; brush garlic with oil and roast in oven for 35 minutes.
- Allow to cool. Squeeze roasted garlic purée from cloves. Reserve.
- Place drained celeriac, potato and kohlrabi in a large pot of cold salted water. Bring to a boil over high heat; reduce heat and allow to simmer for 25 minutes. Add collards during the last 10 minutes of cooking and continue to simmer until all vegetables are tender. Drain.
- Mash vegetables with a potato masher until only a few small lumps remain (to make the purée rustic). Add roasted garlic, cream and nutmeg. Season with salt and pepper to taste. Using a spatula, combine all ingredients. Serve purée alongside grilled red meat or game meat.
Variation: Replace collards by finely chopped fresh chives and savory.