Preheat oven to 350 F. Prepare a 9 x 13 pan with pan spray, set aside.
Wash and peel the Daikon radish. Grate with the larger grating option, toss with the 1 teaspoon of salt, and allow to sit for 10 minutes.
After 10 minutes, Drain the shredded radish, squeezing out any excess moisture.
In the meantime:
In a large pan, cook onion and mushrooms in 1 tablespoon butter until onions are translucent, mushrooms are soft and reduced, and most of the liquid has come out of the veggies.
Add cream cheese to the pan, breaking it up and stirring to fully melt / incorporate well.
Add chicken stock to the pan, whisking well to combine and break up any lumps.
Toss cheddar cheese with xanthan gum, add to the pan. Stir until melted and smooth. Add sour cream and pepper, stirring until well combined/
Finally, add the shredded and squeezed radish, mixing well to combine. Pour into prepared baking pan.
Melt remaining 2 tablespoon butter, mix with pork rinds and Parmesan. Sprinkle evenly over the “potato” mixture.
Cover pan with foil, bake for 40 minutes. Remove foil, allow to bake for another 15 minutes or so, until the topping is crispy and golden.
Serve hot.