Scalloped Potatoes and Celery Root

Directions

1. Peel and gently crush the garlic, wash the thyme, and put them in a saucepan with the cream and buttermilk. Bring it to a simmer and then turn off the heat and let it steep while you get the rest ready.
2. Preheat the oven to 350 and generously butter your pan - I use an oval cast iron and enamel pan but a 9x9 square pyrex is fine too. Whatever you have.
3. Peel the celery. You need uniform slices of potato and celery root so a mandoline set on 1/8" is perfect, but if you haven't got one just slice the potatoes and celery as thinly and evenly as you can.
4. Start with potato - layer the bottom of the pan fish scale style so even though you are only putting in one layer, the whole thing is actually two slices thick. Spoon some of the buttermilk over, just enought to wet the potatoes, then season with a pinch of salt and a little pepper.
5. Now a celery root layer - same thing, overlapping slices, then spoon some buttermilk over, then sprinkle half the parmesan on and a bit more pepper. Repeat this with a potato layer, a celery layer, and then finish with potato.
6. Bake until the roots are soft - stick a knife in to test - about 40-45 minutes depending on your oven. Now sprinkle the grated cheese over the top and put it back in the oven to melt and turn golden brown. Cool until it is sub-nuclear before serving - 10 or 15 minutes.