1Preheat the oven to 400 Degrees F.
2Prepare a roasting pan by lining with parchment paper.
3Set a food processor out.
4Set up the butter in saucepan on the stove top for melting.
5First using a sharp knife, then a vegetable peeler, remove the tough skin and dirt from the Celery Root. I used a knife for the more gnarly part, then a vegetable peeler for the rest.
6Also peel the potatoes. For reference, the fingerlings I used are below. If you don’t happen to find larger fingerlings such as these, do still use the fingerling variety, simply add a few more.
7Cut the peeled celery root and the potatoes into about one-inch cubes and place in a mixing bowl.
8Add olive oil and toss to coat.
9Sprinkle salt evenly over and toss once more.
10Spread the mixture out on your prepped roasting pan and roast at 400 Degrees F for 40 minutes.
11Begin melting the butter over low heat on the stovetop.
12Set the roasting pan on a cooling rack and transfer the roasted celery root and potatoes into a food processor.
13Pulse enough times to throughly chop all of the pieces, about 20 five second pulses.
14Add the melted butter, chicken stock, milk and water and mix until smooth, about 2-3 minutes, longer if necessary.
15Transfer the mash to a mixing bowl and *then* add the chopped thyme. Stir with a spoon to throughly incorporate.
16Serve with a garnish of whole thyme and enjoy this super tasty late-Fall side with your favorite protein!