Preheat the oven to 275 degrees F (135 degrees C) and spread walnuts onto a baking sheet. Toast in the preheated oven until golden brown and fragrant, about 45 minutes. Be careful not to burn them. Set aside once done.

Increase the oven temperature to 375 degrees F (190 degrees C) and crinkle up a piece of aluminum foil to place in an oven-safe dish. This will act as a rack. Place the beet on the foil and bake until just turning tender, about 45 minutes.

Remove the beet from the oven and increase the temperature to 400 degrees F (205 degrees C). Wrap the beet in aluminum foil and let it cool for 15 to 30 minutes before unwrapping and peeling it with a sharp knife. Cut the beet into half-moons.

Brush walnut oil on the bottom and sides of a baking dish, then arrange the beet slices in a single layer. Crumble goat cheese over the beets, season with salt and pepper, and bake for about 15 minutes until the beets are sizzling and the cheese is slightly browned.

Once done, let the dish cool for 10 minutes before drizzling vinegar on top. Garnish with beet greens, chives, and the toasted walnuts. Serve warm.