Celery root and potatoes are a great pairing. I think they give potatoes the little flare they need. I like them in potato pancakes but best of all, mashed potatoes.
2 c red potatoes, unpeeled and large diced
1 1/2 c celery root, large diced
2 T butter -- Kerrygold butter is delectable
2 cloves garlic
3 T milk
1/2 c hard cheese, parmesan, asiago or even an aged cheddar
Salt and Pepper to taste
Boil potatoes and celery root in the same pot together until tender. Drain water.
Add remaining ingredients to the pot and use a potato masher to get to your desired consistency.