OK, before you point out that truffles are hardly frugal, I know. If you had to buy them that is. But we were given a huge one by a (Somerset) farmer who had so many on his estate he didn't know what to do with them.
Unfortunately it started to stink out the fridge so swift action was called for. We had pasta last night with an outrageous amount of truffles and tonight a parsnip, potato and truffle gratin I invented on the spur of the moment and which was actually rather good. (So good that we'd scoffed most of it before I got round to taking a photo.)
Serves 4 as a veggie (it would go well with lamb), 2-3 as a vegetarian main course (we had it with cumin-braised carrots and red kale with garlic and chilli.
2-3 large parsnips
1 medium to large potato
1 small onion
Generous shavings of black or white truffle or a drizzle of truffle oil (but don't overdo it. It's probably safer to mix a few drops into some sunflower or vegetable oil until you get the intensity of flavour you want.)
600ml light vegetable stock
Butter for greasing the dish and dotting over the gratin
Salt and pepper
Pre-heat the oven to 200°C/400°F/Gas 6
Scrub, peel and halve the parsnips, cutting away the woody central core. Slice on a mandolin or finely with a very sharp knife. Peel and slice the potato, onion and truffle to a similar thickness. Lightly butter a largeish baking dish, tip in the vegetables and truffles (or truffle-infused oil) season and mix, then pour over the stock and dot with butter. Bake in the oven for 45-50 minutes until the vegetables are tender and the top crisp and brown. Serve as a side dish with lamb, for example, or as a main with a couple of other veg.
Personally I'd have been tempted to add some cream to this somewhere along the line but my husband is dairy-intolerant :(