I can take no credit for this recipe whatsoever because I discovered it on the BBC Good Food website. Its an Antony Worrall Thompson recipe from Saturday Kitchen (man I miss hungover Saturdays spent watching that show). I happened across a celeriac in the fridge that needed using up, nd having never used one as an ingredient before I had to search for something to do with it. The best answer was a boulangere, which is a fancy French word for a potato bake. You simply peel and slice the celeriac and potatoes and layer it with onions and pour over stock to bake. It sounds underwhelming but the flavour of a celeriac is so underrated. The earthy flavours of the root vegetables seep out when they soak up all of the stock and you get this surprisingly rich flavour. A really good side dish in winter to go with many a pairings. I think you could even mix it up a bit by adding some crispy bacon lardons to add some saltiness to the equation.