I got back from a long trip craving vegetables, this is where that led.
Sweat a coarsely chopped leek in olive oil with some minced garlic. Add grated parsnip, carrot, and celery root, along with a good pinch of salt, and let cook 5-7 minutes. Add chopped spitzkohl (a fine white cabbage) and cook another 5 minutes or so. Stir in a splash of white balsamico, a grind of black pepper, and a spoonful or two of pasta cooking water. Stir in drained, cooked pasta (I used orecchietta) and serve topped with grated grana padano.