I made tartiflette this evening, using celeriac rather than potato. It was lovely!
Rough quantities:
500g celeriac, cut into small chunks, boiled in salted water till just tender (15-20 mins)
2 little packs smoked lardons (they are usually linked packs)
1 onion, finely chopped
2 cloves garlic
100ml white wine
sloosh of double cream
a bay leaf or two
25g butter
Reblochon cheese - around 200-250g
While the celeriac is cooking, fry the onion, lardons, garlic and bayleaves in butter in a frying pan, till all are soft/tender. Add the white wine and the cream and continue to cook gently till all is reduced.
Once the celeriac is cooked, drain it, put it into a casserole dish, add the onion/bacon/wine/cream mixture, stir in and then add the Reblochon. Stir together and season with black pepper.
Bake in the oven with a lid on the dish for around 20 minutes at around 180-200, then take the lid off and continue to cook for another 20 minutes until golden brown on top.
Lovely served with a green salad with a garlicky vinaigrette dressing.